People are attracted to organic growing practices for all sorts of reasons, so I suppose it should not be a surprise that beliefs, practices and approaches between growers can sometimes vary widely. I’m occasionally presented with a question or statement made with the assumption that I use or endorse a growing practice that is popular, and I find myself trying to explain diplomatically why I don’t typically recommend it. Foliar fertilization (the delivery of plant nutrients via sprays applied to leaves) is one of those topics that I find tricky to quickly explain why I don’t think the bang is worth the buck for most growers. A friend once summarized, “It’s like trying to drink a beverage by dumping it over your head!”

Soil Fertility

In natural systems, most plants get all of their mineral nutrition from the soil, specifically the soil water solution — the water that exists in the pore spaces in between solid particles of soil. Mineral nutrients are the elements other than the carbon, hydrogen and oxygen, which make up approximately 95% of a plant’s dry matter, that plants obtain from air and water. Mineral nutrients (the remaining 5% of a plant’s dry matter) are typically divided into macronutrients and micronutrients, separated by their relative abundance in plant tissue. The six macronutrients present in the greatest quantities in plants are, in descending order, nitrogen (N), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P) and sulfur (S). The eight micronutrients are chlorine (Cl), iron (Fe), boron (B), manganese (Mn), zinc (Zn), copper (Cu), molybdenum (Mo) and nickel (Ni). Other nutrients, like silicon (Si), have been shown to be beneficial to plant growth but are not essential for plants to complete their life cycles.

Seems like a lot to keep track of, doesn’t it? In practice, deficiencies in most of these elements in most of the crops grown in New England are rare — provided that growers are practicing good organic practices to support soil health and fertility. Such practices include correcting initial mineral deficiencies in a soil; typically making annual additions of fertilizers containing N, P and K to address the “law of the return” (i.e., replacing the nutrients that leave soil in harvested crops); and maintaining appropriate soil pH and sufficient soil organic matter for the cycling of nutrients and the support of soil life. Other needed fertility additions are often sporadic, such as occasionally varying what type of lime is used every few years to add more calcium or magnesium, and supplying boron to prevent the primary micronutrient deficiency that is encountered in the region. Boron is more likely than other micronutrients to leach from our soils, and is needed by plants in higher quantities relative to other micronutrients (but only by a few crops which have a higher boron need).

What is Foliar Feeding?

Foliar feeding is a method of providing plants with nutrients by dissolving them in water and spraying them on leaves, where they can sometimes enter the leaf through: 1) stomata (microscopic orifices that can be opened and closed by plants to regulate how much water they let out of their leaves, though they open regularly to allow air exchange, letting carbon dioxide in for photosynthesis); and 2) tiny micropores in the leaf cuticle (essentially the waxy skin layer of a leaf, evolved to be nearly waterproof to prevent excessive water loss). The phenomenon of nutrients being able to enter leaves was first proven in several experiments at the University of Michigan about 70 years ago. While it was shown that nutrients can enter plants through their leaves, that rarely happens in nature (carnivorous plants being a big exception) and is not the way that the vast majority of plants have evolved to take in nutrients.

Foliar feeding, an attempt to get dissolved nutrients into plants in the opposite way in which they naturally enter them, is most impactful in distinct circumstances, such as addressing specific micronutrient deficiencies. Macronutrients are needed in such greater quantities by crops than micronutrients that supplying them via foliar feeding is impractical and the concentration needed would greatly increase the risk of leaf burn from the spray. Because both stomata and leaf cuticle have evolved to help a plant limit the amount of water passing through them, foliar-applied nutrients need to be applied in the early morning or late afternoon, when the water they are dissolved in is less likely to evaporate quickly and stomata are more likely to be open. Research has shown that the primary pathway of foliar feeding is not through stomata, however, but instead through micropores in the cuticle layer of a leaf. Stomata are not always open and are often located in the greatest abundance on the underside of leaves, where a spray application is most difficult.

For foliar-applied nutrients to get through the tiny micropores in a leaf cuticle, the plant must be a species with a thinner cuticle layer. Leaf cuticle thickness varies by species and increases with leaf age and exposure to drying environmental conditions — think of a young, soft, greenhouse-grown tomato leaf versus a mature waxy brassica or allium leaf. Micropores are incredibly small, less than 1 nanometer in diameter, and they are lined with negative electrostatic charges, which repel negatively charged nutrient ions (anions, like nitrate, NO₃^–, the most common form of plant available N in organic growing). They are more likely to let neutral or positively charged ions pass through, e.g., cations like calcium (Ca++) or iron (Fe++). Many of these cations are considered to be relatively immobile within plants and are best used to address a specific deficiency in the leaves they are applied to, or perhaps the surrounding tissue, like fruit, but only if applied prior to the development of that surrounding tissue.

Other than some mined minerals, most organic fertilizers are made from plant and animal products — providing nutrients in a complex mixture of larger organic molecules — and most of those nutrient-containing compounds are likely too large to pass through the micropores in a leaf cuticle. Because of these limitations, it is expected that the majority of the nutrients applied in organic foliar fertilizers are actually entering plants only after they have washed down to the soil below, and interacted with the soil ecology.

How Plants Take Up Nutrients from Soil

Plants do use their leaves to acquire mineral nutrients — just not in the same manner that foliar feeding functions. Most everyone reading this likely knows that nutrients in the soil are “sucked up” by plant roots, but did you know that the phenomenon driving the bulk of this movement is the result of water evaporation from leaves, through their stomata? This is called transpiration, and it creates negative pressure at the top of the water column inside a plant stem, which pulls water up from its roots (just like a small amount of suction at the top of a straw can pull a lot of liquid up it). That root suction is subsequently pulling water (and the nutrients dissolved within it) out of the surrounding soil water solution. Roots also uptake a smaller amount of some nutrients directly at the interface of soil particles and the root (or affiliated mycorrhizae). This direct transfer from soil to root (or affiliated mycorrhizae) also functions via water moving into the root, carrying dissolved nutrients into the plant’s water column and to the rest of the plant.

The foundational principles of organic agriculture include two that I would like to highlight here: 1) Organic farming should sustain and enhance the health of soil, plants, animals and humans as one and indivisible; and 2) Organic farming should be based on the living ecological systems and cycles, work with them, emulate them and help sustain them. These principles hopefully guide organic growers to soil-based production systems where we feed the soil to feed the crop, and where foliar feeding is only likely to provide an additional value in rare circumstances — such as when a “rescue” is needed to correct for a larger systemic issue that has not yet been adequately addressed, e.g., excessively high soil pH limiting a plant’s ability to take up micronutrients.

In trying to figure out why some organic growers are drawn to a practice that seems, to me at least, so counter to emulating natural systems, and potentially expensive in terms of time and labor, if not also purchased inputs, I find myself wondering if perhaps we get a bit caught up in what is possible, instead of focusing on what is most easily practicable. Do we seek out practices that allow us to feel as though we’re having a larger impact or are more in control of complex plant-soil-microbial ecologies than we actually are? I think “doing something” is always going to feel better than not, but I wonder if that allows patterns of behavior to get stuck in our minds, where the overall effects of having done something may give us emotional benefits that are oversized relative to the actual economic or yield impacts they have.

I want to be clear that I have no opposition to liquid fertilizer products, though I do strongly encourage growers to compare fertilizer products on the basis of cost per pound of nutrient being supplied. Dry fertilizer products are frequently the more affordable option. I simply recommend saving liquid fertilizer products for situations where it is only possible to add fertility through irrigation. An example would be seedlings that have been growing for a long time, used up all of the fertility available to them from their potting mix, and aren’t soon to be planted out. Liquid applications of boron are probably the easiest way to get a uniform application of the very small amount needed by some crops like brassicas and chenopods — without providing too much (while boron is a necessary plant nutrient, it can quickly reach levels that are toxic to sensitive crops). I’m also not opposed to applying liquid fertilizers as a spray to plant leaves, because, in the words of my plant nutrition professor, “The best thing about foliar feeding is that as soon as it rains the nutrients go into the soil at the base of the plant where it can take them up!”

So, in the end, do I think that foliar feeding is “bad” or “wrong”? Nope! I’m not trying to yuck anyone’s yum — if it works for you, or even if it’s just a way for you to have more fun and engagement with your growing, then that seems reason enough to me to stick with foliar feeding. I just don’t typically recommend the practice for most situations for organic growers and suspect that it’s not usually a “better” option.

If you are interested in foliar fertilization, keep in mind that it is best performed on overcast days when plants are transpiring less and risk of leaf burn is lowest. Young leaves of plants growing in sheltered greenhouse conditions are the most likely to take in nutrients, and small, positively charged ionic forms of nutrients are the most likely to get through the leaf cuticle. Nutrients that are highly mobile inside plants will be just as mobile from root uptake, and nutrients that are less mobile within plants will not travel very far from the leaves where they were absorbed.

This article was originally published in the summer 2023 issue of The Maine Organic Farmer & Gardener. Subscribe today by becoming a member!

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Photos courtesy of Yaicha Cowell

A major reason for preferring pole beans over bush types is to save space. By exploiting your garden’s third dimension, you can harvest much more food from a smaller footprint. Of course, all good things come with a price and in this case it is the extra labor. The effort to collect trellis material like poles is considerable even if, like me, you have many acres of fir or other thinnings, and you use the poles year after year. Of course there’s also the time spent erecting and dismantling the structure, assuming that’s how you support them (there are other ways). I use two styles of pole trellis, which I’ll describe briefly.

Now all of my cultivated area is laid out in permanent beds (not raised), 40 feet long and 4 ½ feet wide with paths measuring 1 ½ feet. For trellis style number one, I make a single furrow down the center of the bed, which of course would be very space-wasting, but I also plant a companion crop down either side (broccoli is a favorite). This allows the bean vines to get more sunlight and they yield accordingly. To set the poles in that center row I use a steel bar to make a deep narrow hole, stick in the bean pole (with a tapered point for greater depth) and stomp in the soil around it. By this method each pole is self-supporting. I set the poles 24 inches apart and sow four to six beans per pole. I usually like to run some slender poles horizontally tied near the top of each vertical pole about 6 feet above the ground. This strengthens the whole array and also allows the beans to run laterally from pole to pole. It’s helpful to have another person holding up the opposite end while I’m tying so the lateral poles remain horizontal and stiff. I always save my skinniest poles with the least amount of taper for those laterals.

Incidentally, every few years the bottom ends of the uprights become punky and weak, so I bust those off, re-pointing if necessary, and the poles become a foot or so shorter. Eventually they become too short for bean poles, after which they serve as tomato stakes or support for pea fence. Some folks, lacking abundant forest thinnings, simply erect a top and bottom rail with twine stretched up and down. Despite the extra effort I greatly prefer the poles for greater wind protection.

The second pole configuration goes like this: I set heavy 8-foot-tall poles in the center row, placed 8-10 feet apart. Between them I lash horizontal poles about 6 feet high, creating a “ridgepole.” Then I make a double row of poles, one on either side and about 2 feet from the bed’s center. These are not quite vertical but lean against the ridgepole to which they are lashed as opposing pairs. The butts of these are simply set in the shallow furrows, as they are fastened at the top and in no danger of falling over. I do however lash them firmly at the top as the vine-laden poles may tend to slide lengthwise in a heavy wind. With a foot or two of pole extending up beyond the ridgepole, the appearance is sort of like a linear teepee.

As far as bean yield goes, the second style is much better (after all, there are two rows), though it leaves no room for a companion crop, as with style number one. Well, actually there is room if you do it right. I sometimes plant a very early-in/early-out crop in the center row (between the upright posts), something like spinach, radishes, lettuce or scallions. Earliness is critical, as the crop must be well-advanced before the rampant bean vines can shade them. Of course, a little bit of shade can help keep those early crops from bolting too soon, but timing is important. I aim to sow the companion crop by early May, which means I must have the posts and top-rails in place then (even though the beans themselves won’t be planted for several weeks yet) lest I trample those crops while planting the beans in June. Even when I’m not on my game enough to do all that in time, the beans still give a bodacious yield.

Let me stop right here and emphasize that I only use this trellis system for green (or string) pole beans, not dry pole beans, for which I have a much easier method — wait for it. But first let me point out that the only pole green bean variety worth growing is Jimenez (I know some folks consider other varieties quite acceptable, but then some folks think Elvis is still alive). It is the most heavy-setting, long-yielding, quality-holding variety I’ve ever seen. It is usable even when the pods are somewhat overgrown and other varieties have gone tough and tasteless. Even after that it makes a superb shell bean and an excellent dry bean resembling a fat pinto. But you go ahead and grow whatever kind you want, it makes no difference to me, just don’t say I didn’t warn you.

Up to now we’ve only talked about green or string beans, but what about dry beans? Many folks feel they haven’t enough room for dry beans. Maybe that’s because they haven’t noticed the price of dry beans in shops, or perhaps they think they need equipment, when all it takes is a flail, or even a heavy stick, and a burlap feed bag to thresh them. As with green beans, pole dry beans yield much more than bush types per square foot. Pole dry beans don’t lend themselves to mechanized harvesting, which is why most store-bought dry beans are bush varieties. If you’re going to hand-pick the pods anyway, why not get a lot more of them?

For me the main difference between green and dry pole beans is that I don’t bother to erect a trellis for the dry beans. Rather I interplant them with sunflowers or grain amaranth (a tallish variety like Opopeo), in effect growing the poles as well as the bean crop, except the sunflowers and amaranth are also valuable food crops, so it’s a win-win. Granted, the pole beans don’t yield quite as well among those tall supporting crops, as the shade has a small adverse effect. How much? I find that pole beans on amaranth yield about 75% as much as those on naked poles, but the great value of the amaranth grain (which seems unaffected by the bean vines) easily compensates for the reduced bean yield.

Here’s an important detail about this combination: sunflowers and amaranth are much more cold-hardy than the beans and so can be planted a few weeks earlier. In fact, they must be started earlier to get a head start on the beans, or else the beans will be ready to climb before these crops have enough height to support them. I start both amaranth and sunflowers in cell-trays (in early May), since direct seeding results in some loss to birds and the tiny amaranth seedlings are indistinguishable from their close relative, red-root pigweed, so how to weed them? I set the amaranth seedlings 2 feet apart in rows 3 feet apart, and the sunflowers are seeded three per cell then transplanted to hills 3 feet asunder, in rows 3 feet apart. By the way, an added benefit of this combination is that the bean vines bind the sunflowers together, reducing lodging when the stalks get heavier.

You may wonder why I don’t plant all pole beans that way, rather than using pole trellises for the fresh green types. Green beans need to be picked frequently throughout the season and the sunflower or amaranth combo can be too dense and tangled to access as the season progresses, whereas the dry beans can be harvested at about the same time as the support crop, when both have matured and dried back, so that thrashing around in there will do little damage.

In addition to producing a greater yield, some folks feel that pole beans are fuller flavored than bush types. I’m partly in that camp, although there’s so much variation between varieties of either type that I’m not certain of that. Pole beans are less impacted by fall frosts, not because they’re any more frost-resistant but rather being high above the ground protects the upper part of the plant, while only the lower leaves may be injured. I’ve also noticed that pole beans exhibit more extreme variation in seed size and color. I suspect that may be because so many pole varieties are old heirlooms that may have been selected for aesthetic qualities over commercial traits.

About the author: Will Bonsall lives in Industry, Maine, where he directs Scatterseed Project, a seed-saving enterprise. He is the author of “Will Bonsall’s Essential Guide to Radical Self-Reliant Gardening” (Chelsea Green, 2015). And indeed, he is also a distant cousin of another exemplary Maine horticulturist: Tom Vigue. You can contact Will at wabonsall@gmail.com.

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Winter squash look ready to harvest before they actually are mature. It is important to wait for maturity to maximize storage life and eating quality, whenever possible. The fruit of most squash varieties reach full size by 20 days after pollination (fruit set). Accumulation of starch and other dry matter peaks at about 30-35 days after pollination, but the fruit is not fully mature until the seeds are fully developed, which occurs about 55 days after pollination. This can vary somewhat by squash species (Cucurbita maxima, C. moschata and C. pepo) and variety, however, and a hot dry season can sometimes push squash to mature faster. Keeping track of “days after pollination” is perhaps a less common task, but it may be easier for growers that practice cucumber beetle exclusion to get “in the ballpark” if they record the date when row cover or exclusion netting was removed to first allow pollinators access to flowers.

Dr. Brent Loy, late University of New Hampshire professor emeritus and New Hampshire Agricultural Experiment Station researcher, was an expert on this subject, and stressed the importance of maintaining healthy plants until at least 50 days after fruit set because photosynthesis is essential to the development of sugars and dry matter in the fruit. A squash that is picked too early will continue to develop seeds, but it does so by depleting dry matter of the fruit, thereby reducing eating quality. However, fruit should still be harvested if squash or pumpkin plants lose their leaf coverage prematurely, whether because of powdery mildew or downy mildew or some other cause, as the fruit quality and dry matter content stop improving, and exposed fruit are left susceptible to sunburn and pest and disease risks. Foliar diseases can also greatly reduce the quality of pumpkin handles (stems), which reduces their usefulness and marketability as jack-o’-lantern pumpkins. The other important factor influencing harvest timing is the threat of chilling injury, which occurs incrementally any time the fruits are exposed to temperatures below 50 degrees Fahrenheit. Chilling injury is not as severe as frost or freezing damage, but chilling injury accumulates and the more hours that fruit are exposed to chilling temperatures the greater their potential for storage lifespan to be negatively impacted.

Curing and storage

Although fruit and seed maturity are similar across the three main species of edible winter squashes and pumpkins, curing and storage recommendations vary by type. Greater detail follows below, but in general, the Cucurbita pepo varieties require little to no storage before eating (provided they were allowed to reach maturity before harvest), while the C. maxima and C. moschata varieties may benefit from curing and almost always require at least some time in storage before they will have a desirable eating quality. The time between harvest and eating is critical, for the squash varieties that require it, to develop flavor and transform starches into sugars; however, not all varieties require it for acceptable eating quality and curing may even reduce some varieties’ storage lifespan. 

For the varieties that benefit from it, curing is best performed over 5-10 days following harvest, at a relatively high temperature (80-85 F) and relative humidity (80-85%). These conditions help to harden the skin of the fruits and accelerate wound healing, as well as to kick-start the conversion of starches to sugars inside the fruit. A greenhouse or high tunnel is often an ideal location to cure squash, provided that temperatures are not allowed to get too high or too low (below 60 F), and ideally with consideration given to protecting fruit from sun damage. If squash is intended to be in storage for several months, a separate curing step is not always necessary.

The ideal storage temperatures for pumpkins and squash are between 50-60 F because that is the sweet spot where fruit does not accumulate chilling injury, but is cool enough to slow respiration — which gradually reduces fruit weight. If possible, relative humidity should be kept between 50-70% to minimize desiccation or decay organism growth. Strive to only be placing fruit into storage that is free of signs of disease, pests or unhealed wounds.

Cucurbita maxima | Kabocha, hubbard and buttercup squashes

Kabocha, hubbard and buttercup (C. maxima) varieties can be harvested before complete seed maturation, at about 40 to 45 days after fruit set, when the fruit is still bright. That’s when the rind is hardest, making the fruit less likely to be damaged in storage. Stems will typically become dry and corky by harvest. The fruit are susceptible to sunburn as the vines die back, so in cases of foliar disease, it’s best to get them harvested and out of direct sun to prevent the rind from turning brown or, with extreme sunburn, white. Kabocha squash have a high dry matter content and small seed cavity, making seed maturation off the vine less of a concern, however, once harvested they should be cured and then stored at room temperature for a minimum of 10 to 20 days to allow sugars to reach acceptable levels. Most C. maxima varieties (other than mini-kabochas and red-skinned kabochas) are starchy at harvest, however, and do not reach optimal eating quality until one to two months of storage time have passed. C. maxima varieties can often store for four to six months after harvest.

C. pepo | Acorn squash, most pie pumpkins, delicata squash and spaghetti squash

Varieties of this species can typically be eaten at harvest, if allowed to fully mature, and may even have reduced storage lifespan. With the exception of spaghetti squash, these varieties will often store for two to three months. Spaghetti squash often store poorly. 

Pie pumpkins should be harvested after their skin fully turns orange, when possible. A mostly orange fruit will continue to color up off the plant however. Acorn squash are misleading because they reach full size and develop a dark green-to-black mature color about two weeks after fruit set — 40 to 50 days before they should be harvested. Loy recommended that a better way to judge maturity is to look at the rind where it touches the ground. Immature squash have a light green or light yellow ground color, whereas mature squash have a dark orange ground spot. Immature acorn squash have low sugar levels and although they will develop sweetness after harvest, they do so by depleting the dry starchy matter to convert it to sugars. This means storage life is shortened and eating quality declines.

C. moschata | Butternut squash, some pie pumpkins

Butternut squash (C. moschata) are easier to judge by sight because they don’t acquire their characteristic tan color until late in development, 35 days or more after fruit set. If the weather stays frost-free, they should be allowed to remain on the plants until 55 days after fruit set (two to three weeks after turning tan). Butternut squash should be stored for 60 days at 56-60 F, with relative humidity between 50-70% to allow starch conversion into sugar for optimal eating quality. Carotenoid content also increases in storage, making the butternut squash more nutritious and visually appealing after storage for a couple months. To accelerate maturity and increase sweetness, Loy found that butternuts cured at warm temperatures (up to 85 F) for two weeks develop acceptable levels of sugars. C. moschata varieties can often store for at least four to six months.

Sources

Higgins, G. and R. Hazzard. 2022. “Pumpkin & Winter Squash Harvest, Curing & Storage.” UMass Extension Vegetable Notes, Volume 34: Number 18, August 18, 2022.

https://ag.umass.edu/sites/ag.umass.edu/files/newsletters/august_18_2022_vegetable_notes.pdf

Johnny’s Selected Seeds. 2022. “Eating Quality in Winter Squash & Edible Pumpkins.” Accessed August 24, 2022.

https://www.johnnyseeds.com/growers-library/vegetables/winter-squash/eating-quality-in-winter-squashes.html

Loy, Brent. “Maximizing Yield and Eating Quality in Winter Squash – A Grower’s Paradox.” Department of Biological Sciences, University of New Hampshire.

https://www.hort.cornell.edu/expo/proceedings/2011/Vine%20Crops/Maximizing%20Yield%20and%20Eating%20Quality%20in%20Winter%20Squash%2011.pdf

Sideman, Eric. “Winter Squash Looks Ready, Should I Harvest?” MOFGA Pest Report, August 14, 2014.

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Summer may feel like the middle of the growing season, but the warmest days mark a time when Maine gardeners can start a new round of crops for autumn harvest.

Emily Pence, seeds field coordinator at Fedco Seeds in Clinton, says that planting in the summer can make for an easier growing experience for some crops.

“Climate change seems to be making the spring in our area very unpredictable, and recently, hot and dry, which doesn’t bode that well for greens and Brassicas,” Pence says. “Fall seems a little more reliable for now.”

Another benefit to summer planting is decreased weed pressure. “After the summer solstice, many weeds start to focus their energy on seed production, which means weeds going to seed need to be managed quickly to prevent spread, but there are less new weeds growing,” says Pence.

Perhaps most importantly, the flavor of many crops will benefit from the timing. “The summer heat stresses some things and brings out bitter flavors,” says Pence. “Also, some plants just aren’t as tasty in the heat because they are relaxed. The cold signifies to a lot of plants that they need to start storing sugars for energy, which makes them taste sweeter.”

Here are several crops that growers can plant this summer.

Beans

Beans, if successively planted every few weeks, can yield throughout the season. Beans that mature in the fall tend to be more tender and flavorful than those that pop off in the summer heat.

Pence recommends direct seeding beans the first week of June for harvest from August to October. She loves all beans, but favors pole beans. Northeaster and Kentucky Wonder will mature in under 70 days, which leaves plenty of time for multiple harvests if planted in early summer.

This time of year, gardeners can also plant plump and creamy Maine Sunset, the bean hole classic Kenearly and the reliable, hardy and easily shelled Vermont Cranberry.

Potatoes

Planting potatoes in the early summer helps to evade potato beetles when the pest is most active.

“Late planting potatoes will mean that the potato beetles emerge before the potato greens have,” says Noah Dillard, potatoes, onions and exotics coordinator at Fedco. “They have to travel elsewhere to find food and will have left your field by the time the potatoes are up.”

Dillard says planting by mid-June is “late enough.”

Late planting means that potatoes, which are sensitive to day length, will spend less time in the tuber initiation and bulking stages. Fewer, smaller tubers will form, but the flavor and quality aren’t impacted.

Dillard says that most mid- to late-season potatoes could be planted for fall harvest, and picking a favorite makes him “feel like a parent being asked who is [his] favorite child.” When pushed, Carola wins for flavor, but can be finicky to grow.

“My preference for wintertime is to have a cellar full of different kinds of potatoes to choose from,” says Dillard.

Winter Squash

Direct sowing winter squash in early June will have the fruits harvestable by early October.

Pence prefers Cucurbita maxima varieties, including Kabocha, Buttercup and the lumpy Hubbard.

For fans of aesthetic gourds, Nathaniel Gorlin-Crenshaw, product technician at Johnny’s Selected Seeds, recommends Duchess, a new pumpkin from the company’s breeding program, which prolifically produces medium-sized fruit with a rich orange hue and gorgeous wrinkles. His favorite squash for eating, though, is Winter Sweet, a Kabocha with a charming mottled blue-gray exterior and sweet flaky flesh.

Beets

Beets are adapted to grow in cool temperatures, so they are perfect to plant late summer. They thrive best when the days are warm but not hot — between 60 and 70 degrees Fahrenheit —and nights cool, but not cold, as beets might go to seed at temperatures below 50. Successive plantings are possible throughout the summer as long as daytime temperatures don’t top 75.

Jonalyn Burt, trial technician at Johnny’s, recommends Chioggia Guardsmark for its unexpected colors.

Pence is a fan of Early Wonder Tall Top, prized by home gardeners and commercial gardeners alike for its disease resistance, vitality and clean bunches. She also loves 3 Root Grex.

“A grex is a mixture of varieties growing together and encouraged to cross-pollinate,” Pence explains. “Instead of crossing two parents to create offspring, which results in what is known as a hybrid, the breeder crosses dozens, and selects the best ones. Grexes have high genetic diversity and resilience.”

This grex is particularly striking. The cross between Yellow Intermediate, Crosby Purple Egyptian and Lutz Saladleaf results in three distinct colors: rich pinkish-red, opulent gold and iridescent orange.

Carrots

When maturing in warm weather, carrots often lack the sweetness of those grown at cooler temperatures. Ideally, carrots are sown when the weather is warm and mature as it begins to cool, making them the perfect crop to sow from mid-summer onwards.

Daniel Yoder, trial technician at Johnny’s, recommends Bolero for its flavor, quick maturation, storage ability and leaf blight resistance. Pence suggests sowing the high-yielding Yaya, crisp-tasting Nantes Fancy, and Scarlet Nantes, a Fedco bestseller.

Brassicas

Fall brassicas like broccoli, radishes, turnips, cauliflower and kale should be planted mid-to-late summer, six to eight weeks before the first frost.

Pence’s favorite is Piracicaba, a non-heading broccoli with loose heads, ample side shoots and succulent stalks.

For a broccoli that was bred to withstand heat, it also has good frost tolerance. “They can produce a steady crop of florets well into October,” says Pence.

Rachel Katz, product technician at Johnny’s, says baby-leaf brassicas are great to direct seed in the fall, as they hold up to frost and become sweeter and darker in color as the days cool.

“I seed them around mid-August for fall harvesting,” Katz says. “Flea beetle pressure is lower in the fall, too, so you don’t even have to cover them with row cover.”

Radishes are another fun crop for late summer planting because they mature quickly and come in many colors. Katz favors purple-and-white streaked KN-Bravo and deep pink Red Meat for seeding in late July for winter storage. Pence recommends Watermelon with its tender rosy flesh; the crisp Plum Purple; and tangy violet Mini Purple Daikon.

An autumn crop of turnips seeded in late summer is also sweeter and more tender than a spring crop. Pence likes bright white Oasis Turnip and Gilfeather Turnip, which is a bulky-but-silky cross between a rutabaga and a true turnip.

Bok choy is another wonderful brassica for fall planting. Katz recommends Asian Delight and Li Ren Choi, both baby bok choy varieties perfect for quick kitchen prep.

Katz also advocates for Tokyo Bekana, a variety of non-heading Chinese cabbage with a soft, ruffled texture.

“It’s great direct seeded as baby leaf or thinned to 4 inches and bunched as mini heads,” says Katz. “It’s one of our favorite greens on the research farm because of its beautiful blonde color, buttery leaf and crisp white rib.”

Lettuce

Fast-growing, cold-loving lettuce is a relatively low-stress crop for gardeners. However, lettuce seeds can be sensitive to warm conditions when germinating, so they are best planted in the late summer for harvest in the fall.

“I always plant several successions of leafy herbs, lettuce, arugula and mustard greens,” Pence says. Pirat Butterhead, Olga, Italienischer and Marshall are favorites.

“I stop and gasp every time I walk by Marshall lettuce in the field.” Pence adds that this deep burgundy romaine could be grown as an ornamental. “They definitely should be eaten though; they are one of the best tasting romaine lettuces I have ever had. They are very heat tolerant, without internal breakdown or developing bitterness, so they would do well with unexpected September heat.”

Johnny’s Five Star Greenhouse Lettuce Mix — a combination of green and red oakleaf, red romaine, and green and red leaf lettuces — works well for fall-harvested baby leaf.

“I often get downy mildew on my lettuce in the fall, but this mix is updated regularly to maintain full downy mildew resistance,” says Katz. “The varieties also have nice loft and uniformity that stay a nice salad size for a long time.”

No matter what gardeners are putting in the ground, delicate seedlings need extra care and watering in the summer heat, particularly on dry days. Hotter and wetter summers make crops mature faster, says Pence, so growers might want to start planting a bit later, especially with milder falls.

Sam Schipani is a writer based in Bangor. For three years, she was a reporter for the Bangor Daily News, where she covered food, farming and sustainable living. Prior to moving to Maine, Schipani has written for Sierra, Smithsonian, Earth Island Journal and American Farm Publications.

This article was originally published in the summer 2022 issue of The Maine Organic Farmer & Gardener. For planting dates, view MOFGA’s seed planting calendar. Interested in more gardening resources? Sign up for MOFGA’s Gardener Newsletter.

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By Dr. Gladis Zinati, Director of the Vegetable Systems Trial at Rodale Institute

Beginning in the early 1900s and coinciding with the Industrial Revolution, industrial farming was characterized by intensive farming of crops and animals where large-scale monoculture and high levels of chemical pesticides and synthetic fertilizers were routinely used.

After World War II, the combined effects of technological advances in large-scale machinery along with accelerated breeding programs enhanced monoculture production and accelerated farmer reliance on machinery and widespread use of chemical fertilizers and pesticides. For example, nitrogen fertilizer used for growing crops in the United States nearly doubled (about 11 million tons) between 1960 and 1983 and stabilized at that level until 2010. Similarly, there was a tenfold increase in pesticides use in U.S. agriculture during the same period, averaging 400 million pounds of pesticide active ingredient through 2010.

Soil health is an important foundation of a healthy farm ecosystem. Most of the farming techniques that have been employed in industrial crop production have contributed to soil degradation over time. Regular applications of agrochemicals in cropping systems further diminished the health of soil. Agrochemicals include herbicides, pesticides and fertilizer amendments. These chemicals interact with soil microorganisms including bacteria, fungi and earthworms which all contribute to a healthy plant rhizosphere and provide a range of benefits within cropping systems. However, these organisms are sensitive to variations in the environment, such as tillage and agrochemical inputs, leading to diminished microbial diversity, functionality, and adaptability to rapid environmental shifts.

It has been documented that soil health declines at a rapid rate when tillage practices are employed intensively and annually. Tillage and cultivation of soil are commonly used for controlling weeds, plowing under cover crop biomass, and preparing beds for seeding. Each tillage activity exposes the soil organic matter to oxygen, causing the release of carbon in the form of carbon dioxide into the atmosphere. Recent data presented at the COP26 (Conference of the Parties), held in Glasgow, Scotland, in 2021, showed that carbon dioxide concentration in the atmosphere has been continuously increasing since 1960 (when the level was 312 parts per million), reaching 411.51 parts per million as of November 5, 2021. Carbon dioxide is one of the greenhouse gases that contribute to heating up of the planet.

Intensive tillage compounded by applications of agrochemicals degrades soil health by reducing soil aggregate stability, increasing compaction, and increasing chances of soil erosion. Heavy rainstorms on degraded soils provide potential opportunities for runoff loaded with toxic chemicals and fertilizers that pollute water systems.

In the past two decades, researchers documented the negative impact of human exposure to pesticides either through direct exposure, air, water, or consumption of food contaminated with pesticide residues. Research data published between 2002 and 2005 showed that pesticide residues were detected in 73% of the 20 fruits and vegetables that were tested. Data by the Pesticide Action Network in 2012 have shown an increase in percent of mental disorder and children cancer cases since 1975 due to exposure to pesticides in foods.

Researchers have also showed that fruits and vegetables have increased in size with the introduction of breeding programs post World War II. The increase in size of fruits and vegetables has led to dilution of nutrients in harvested crops. Studies have shown that the greater the size of fruits and vegetables, the greater the dilution effect on nutrients.

Unlike agronomic crops, intensive vegetable production includes multiple cultivations and tillage of soil during the growing season. The use of moldboard plow, discs, and other cultivators are used to mix cover crops with soil, prepare seed beds, and control weeds. All these farm activities, when practiced over multiple years, lead to soil degradation and consequently negatively impact plant health and nutrient density. Impacts can be more dramatic in organic cropping systems because vegetable growers don’t use herbicides that are used by conventional growers. However, using herbicides and other agrochemicals can be detrimental to soil microorganisms, the nutrient recyclers, when used in conventional systems.

The Solution

The system is broken and soils in the United States as well across the globe have degraded over the past 70 years. However, the effects of soil degradation can be mitigated, prevented, and even reversed by implementing regenerative farming techniques and land management. These techniques include cover cropping, crop rotation, reduction in soil disturbance, freeing soil from toxic chemicals, and amending soils with organic-based materials such as compost. Healthy soil is soil that is capable of sequestering carbon from the atmosphere, provides available nutrients to crops during the growing season, and is free from toxic chemicals that impact soil microbes and buildup of chemical residues in soil and harvestable crops. A healthy soil has good structure that allows easy infiltration of water and is rich in diverse living organisms that are dynamic in cycling nutrients for plant uptake. All these properties not only sustain crop productivity but also animals and humans. However, all these techniques may not contribute to production of nutrient-dense crops, sustainability, and resilience to changes in weather if they are not coherently arranged with proper farming systems and management practices.

There is a plethora of published research showing the impact of cropping systems on soil health and management practices for production of agronomic crops, suppression of root diseases, and weed control. However, there is a lack of information on how management practices may impact soil health and consequently vegetable nutrient density when grown in industrial and regenerative cropping systems.

The Vegetable Systems Trial (VST)

In 2016, the Vegetable Systems Trial (VST) was initiated at Rodale Institute in Kutztown, Pennsylvania, to assess side-by-side the impact of management practices on soil health and nutrient density in vegetable crops grown in organic and conventional cropping systems. The goal of this long-term trial is to deliver science-based information that links the soil health to plant health and human health. The vegetable growers, consumers and the public at large are all beneficiaries of such information.

In the VST, soil health and plant nutrients are evaluated in two cropping systems: the organic system that includes organic or biologically based inputs and the conventional system, representing the industrial farming system, that includes agrochemical inputs such as synthetic fertilizers and pesticides.

Within each cropping system, two tillage practices are implemented. The intensive tillage which entails the use of a moldboard plow and discing for mixing the cover crop biomass with the soil and preparing beds laid with black plastic mulch. On the other hand, reduced tillage is implemented to minimize soil disturbance and increase buildup of soil organic matter over time. Regenerative techniques are mainly practiced in organic systems, where the cover crop biomass composed of hairy vetch (legume) and cereal rye (grass) is roll-crimped in spring to form a mulch and vegetable crops are either seeded using no-till seeders (e.g., snap beans) or transplanted using no-till transplanters (e.g., butternut winter squash). In comparison, the chemical conventional system includes the burndown of cover crop biomass (cereal rye) using herbicides in spring and before planting vegetable crops. As for potato production with reduced tillage practice, the chisel plow is considered a less aggressive implement to use for plowing and mixing the cover crop biomass with soil compared to the moldboard plow.

Collection and Interpretation of Data from VST

The data collected from the VST is used to assess the changes in soil health and crop nutrient quality caused by the implementation of management practices within cropping systems over multiple years. While some soil health indicators may change over a short period of time, others may take longer to change. The multi-year data collected from the VST trial will aid in defining the link between soil health and crop nutrient density and subsequently their impact on human health.

Throughout the growing season, soil health is assessed for physical, chemical, and biological properties in samples collected from the plow layer (8 inches). In addition, every three years, marking the completion of a crop rotation in the trial, deep soil cores are collected in the soil profile (up to 40 inches deep) and assessed for changes in soil health indicators when compared to baseline reference data collected in 2016. For plant health and nutrient quality, all crops are monitored for pests and diseases and the harvested crops are graded for quality and quantity. Ground freeze-dried samples of harvested vegetable crops are analyzed for various vitamins, phytonutrients and mineral nutrients.

Soil Health Indicators

Two major soil health indicators will be discussed in this article. These include soil protein and labile soil carbon. Soil protein is an organic form of soil nitrogen from plants and microbes. It is an active pool for readily available nitrogen that is recycled and taken up by plants. This pool of proteins acts as a reservoir for the microbial community. Thus, since this pool depends on inputs of nitrogenous sources and availability to crops, we expect that protein levels may change over time. Labile organic carbon (also known as POXC) is another measurement of the active pool of soil organic matter. Simply, it is the measurement of how much soil organic matter is utilized by soil microorganisms by oxidizing it (use of oxygen) to get their energy for various functions. Published research has shown that this indicator can be more sensitive to management changes over time.

Recent and Major Findings from the VST

Preliminary and major findings on soil health in the VSTinclude those related to soil protein and labile organic carbon. Between 2016 and 2019, soil protein levels in the top 8 inches of soil increased by 37% in the organic cropping system. Interestingly, there was no change in soil protein levels in the conventional system between 2016 and 2019. The management practices did not influence soil protein levels. As time elapses, changes in the conventional system may become evident especially because the nitrogen source is urea, a synthetic non-organic fertilizer. In the next few years, these measurements will be repeated to learn more about impact of cropping systems and management practices on soil protein over time.

Similarly, labile organic carbon increased by 25% in the organic system and significantly more than in the conventional system (which had a 15% increase) between 2016 and 2019 in the top 8 inches of soil. Unlike soil protein, an increase in labile organic carbon levels was expected. Such increases can be attributed to inclusion of cereal rye, a cover crop with a high carbon-to-nitrogen ratio, in both systems. The labile organic carbon in both systems ranged between 700 and 1,100 parts per million. According to Cornell Soil Health Laboratory, the soil in the VST assessed in the top 8-inch plow layer is considered healthy (scored 80 to 90%) after three growing seasons from inception.

How Do Soil Health Results Link to Vegetable Nutrient Quality?

Total protein levels in sweet corn and potato followed a similar trend of soil protein in that organic sweet corn had significantly greater total protein levels (10.6%) than conventional levels (9.6%) in 2019. Organic Lehigh and Purple Majesty potato tubers had significantly greater total proteins (11.5% and 10.5% respectively) when compared to conventional (10.5% and 9.4% respectively).

On the other hand, total phenols in potato tubers varied with potato cultivar and tillage practice. Phenols in vegetables and fruits have anti-inflammatory, anti-viral and anti-bacterial properties and boost the human immune system. Purple Majesty tubers (purple flesh and skin) were three times greater in total phenols (5 milligrams GAE/g [gallic acid equivalents per gram] dry weight) when compared to Lehigh. Purple Majesty is more sensitive to management practices than Lehigh, and potato tubers harvested from plots managed with intensive tillage showed a slight increase in total phenols over those managed with reduced tillage. In comparison, total phenols in Lehigh potato did not differ with management practice.

The data presented here from the Vegetable Systems Trial show that certain soil health indicators are impacted by the cropping system regardless of the management practice. Soil protein and labile carbon levels mirrored sweet corn and potato protein levels and varied with cropping systems. However, management practices were found to impact total phenols in one of two tested potato cultivars. Additional data collected in the next five to ten years will verify the factors that contribute to short- and long-term changes in soil health and crop nutrient density.

Gladis Zinati was the keynote speaker at the 2021 Farmer to Farmer Conference. Her address, entitled “Linking Soil Health to Plant Health,” is archived on MOFGA’s YouTube channel. It was also broadcast on Common Ground Radio on WERU Community Radio and is available to listen to as a podcast at weru.org.

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-Jesse Stevens 

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Farmers developed soil-less mixes for use in containers for seedlings because field soil does not work well. Soil alone is heavy and poorly aerated. It tends to become waterlogged and sticky when wet. Then it shrinks when it dries, pulls away from the container edges and turns into a little brick, which is difficult for plant roots to penetrate. Furthermore, field soil may be a source of diseases that slow growth and kill seedlings.

An ideal soil mix will:

• be dense enough to hold up the seedling
• retain moisture
• be porous enough so that excess water drains and the mix remains aerated
• be free of weed seeds and plant pathogens
• have low salinity (1 to 2 mmhos)
• have a pH 6.5
• have adequate amounts of nutrients available

Most commercial mixes on the market do not meet organic standards because they contain synthetic sources of nutrients. Basically, they are mixes of peat, perlite, vermiculite, a wetting agent, lime and chemical salts of the major nutrients. Some commercial mixes do meet organic standards. They too use peat, but instead of synthetic chemicals the organic mixes rely on compost, natural rock powders and organic sources of nutrients. Johnny’s Selected Seeds and Fedco both carry approved seed starting mixes. For contact information about other commercial mixes available in Maine, call the MOFGA office at (207) 568-4142.

Many growers make their own mixes. Common ingredients for the major portion of mixes include peat, sand, vermiculite, perlite, compost and lime. Below are the basic characteristics of each of these. When designing a mix, growers look at what they need from each ingredient with regard to moisture holding capacity, aeration, nutrients, etc and then determine proportions that work.

Here are the major characteristics of these ingredients:

Peat

• high moisture holding capacity
• low pH (compensate with limestone by adding 2 to 3% by weight at least five days before planting)
• very little to no nutrients
• Questionably renewable resource. The Canadian peat industry claims that they are harvesting peat from bogs at a rate no higher than it grows. Still, some growers will substitute coir (coconut fibers) or leaf mold. The coconut fibers have their own environmental issue since they have to be shipped long distances. And, if you use coir make sure it is pesticide free.

Sand

• increases density for greater support
• improves aeration
• contains no nutrients

Vermiculite

• good water holding capacity
• improves aeration
• neutral pH and good buffering capacity
• high cation exchange capacity (CEC)
• sterile
• contains some magnesium and potassium

Perlite

• greatly improves aeration
• neutral pH but no buffering capacity
• no CEC
• no nutrients
• sterile

Compost

• good source of plant nutrients
• good moisture holding capacity
• high CEC
• becomes waterlogged easily

Compost for a potting soil should be the best compost. It must be mature, with a proper C:N ratio, be low in salts that would interfere with seed germination and be porous. An optimum analysis for compost, which can be obtained by sending samples to the University of Maine Soils Lab, should be:

pH: 6-6.5
salt: 1-3 mmhos
C:N: 15-25:1
bulk density: 10-30 lb/ft3
NO3 – (nitrate nitrogen): > 500 ppm
NH4 + (ammonium nitrogen): < 100 ppm

Here are some recipes. I suggest that you try your own based on these and the information above, and try it before you do any large plantings. The advantage of commercial mixes is that they are consistent, and the disadvantage of homemade mixes is that they often are not dependably consistent.

Recipe #1

5 gal. compost
5 gal. black peat
5 gal. brown peat
5 gal. perlite
1 cup blood meal
1 cup greensand
1 cup rock phosphate

Recipe #2

5 gal. garden topsoil
5 gal. compost
2 gal. brown peat
2 gal. vermiculite
2 cups bone meal
1/2 cup perlite
1 cup blood meal

Recipe #3

5 gal. brown peat
5 gal. black peat
5 gal. compost
5 gal. sand
1 cup greensand
1 cup colloidal phosphate
1 to 2 cups crab meal

Recipe #4

5 gal. black peat
5 gal. brown peat
1.5 gal. sand
1/2 cup lime
1 cup blood meal
1 cup rock phosphate
1 cup greensand
1.5 gal. garden soil

NOTE: All of these mixes have concentrated sources of nitrogen, e.g., blood meal or crab meal. You can substitute alfalfa meal (not pellets which mold) or soy bean meal. You can also make any of these mixes without that and provide the needed nitrogen in periodic watering with compost tea or fish emulsion.

1. When using blood meal be aware that when it first gets wet and starts to decompose, it gives off ammonia that can kill plant roots. I suggest that you wet the potting soil about a week before you plant into it and make sure it stays aerated during that week.

2. When using topsoil you may want to “sterilize” it because of potential plant pathogens. This can be done on a small scale in your home oven. Bake it at 350oF for 45 minutes or until the soil is about 180o F for 30 minutes. This should kill the pathogens and yet leave enough of the soil microbes alive.

3. Black peat is a more humified peat that is sometime referred to as peat humus. It is not often found in commercial markets, but if you look for the darkest peat with short stems it will do fine. True black peat cannot be used alone because it becomes slimy and muddy when wet. I have heard from one grower who when it became impossible to find the black peat that they just dropped it from the mix and increased the amount of compost a bit.

Last published November 2007

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Introduction

The science of gardening is complex, but the actual practice is simple. The central goal of organic gardening is to maintain or improve the ability of the soil to support plant life as it produces a crop of vegetables each year. That ability depends on a dynamic balance between minerals and the animal, microbial, fungal and plant members of the community. Concern for the long-term productivity of the soil contrasts with the conventional gardener’s concern with short-term plant nutrition and is exemplified by the common slogan of organic gardeners, “Feed the soil and it will feed the plants.”

A groundswell of interest in organic gardening has developed over the past few decades. Paralleling this interest, a large number of books have been published. However, too often they get carried away with the tenets of the practice and become long-winded. Our bulletin passes on the nitty-gritty facts and teaches you the basic methods of caring for your plants and soil and protecting your plants from the most common pests. Other MOFGA bulletins and fact sheets (see www.mofga.org) build on this basic bulletin.

I. Getting Started

Choosing a site. Most vegetables require “full sunlight,” commonly defined as at least five or six hours of direct sun during the middle of the day. Excessive shading results in spindly, weak plants that are susceptible to disease and produce little fruit. If you have no sunny sites, do not put aside the idea of a garden. A few vegetables, although they often will grow quite slowly, will produce in partial shade. These include beets, carrots, kale, lettuce, peas and spinach. If possible, the garden should be close to the kitchen, not only for convenience, but because woodchucks, rabbits and deer are a little less likely to venture close to the house.

An important factor to consider when choosing the site is the soil. Gardening can work well in many types of soil, but common vegetables do best, with the least effort by the gardener, on friable (easily crumbled), porous soils. A deep sandy loam is ideal, as it will provide good aeration and allow root penetration. A soil that is too sandy will not hold water well and will allow the soluble nutrients to be leached away (carried out of the root zone by water). In contrast, a soil with too much clay will hold nutrients and water but will offer poor aeration and may become waterlogged at times.

Sites to avoid include: 1) areas composed of “fill dirt.” Fill usually consists of bottom soil (soil that was beneath the richer topsoil), stones and debris. The fertility is usually very poor; 2) depressions that remain wet after brief rains. Such wet soil has very poor aeration, and the roots of vegetables need oxygen.

If you create your garden site in an old field or lawn, you are likely to have a few problems during the first season. First, nitrogen will be unavailable to the plants while the grass is decomposing because of the rapid growth of bacteria. As the number of bacteria increases in response to the sudden increase in food (the sod), these microorganisms use most of the available nitrogen to build their own cells. Only as the bacteria themselves decompose will the nitrogen be released from the bacterial bodies and become available to the vegetable crops. The second problem is weeds: Many of the perennial grasses that you turned under when preparing the garden spot will grow right back. Also, many species of insects that live in the sod, such as grubs and wireworms, may become serious pests of vegetable crops the first year. Ideally, you should prepare your garden site far enough in advance to avoid these problems. The following is an example of how you could prepare sod ground for a garden:

• Take a soil test in order to determine fertilizer requirements. The soil test kit that you can obtain at your local Cooperative Extension Service office has directions for taking a soil test.
• Turn over sod in late summer the year before you intend to plant the garden. Add lime, rock phosphate and manure as recommended by a soil test, and plant a winter cover crop such as winter rye (or oats if you do not have equipment that can turn under the rye the following spring. Oats are winter killed, so they are easy to turn under or pull aside when you’re ready to plant.)
• Turn the cover crop under early in the spring, once the soil is no longer muddy but at least a few weeks before planting the garden.
• Plant vegetables that are fairly competitive—such as tomatoes, corn, squash, beans or cole crops—the first year, as many weeds may still be prevalent.
• Keep the area well weeded all summer. The vegetables listed in step 4, above, can all be mulched, which will help control weeds.
• Cut the grass short around the border of the garden to avoid a source of weed seeds.

Garden Size. The size of a garden depends on the availability of space, water and your time—not only to plant, but to care for the garden. The variety and amount of vegetables you want, and whether or not you will preserve part of the harvest, are also major considerations. Consider starting small and expanding when you are sure you can maintain a larger garden. If space is limited, you probably should not plant corn, squash or melons, because they require large amounts of space. See the discussion of each vegetable for estimated yields per 50 feet of row.

Soil Amendments. Almost all soil can support some kind of plant life, but for a good yield of garden vegetables the soil must provide ample basic requirements. Those requirements include water, air and minerals. Soil structure refers to physical features that determine the ability of the soil to hold water and air, while soil fertility refers to the ability of the soil to provide the nutrients required by plants. Both structure and fertility can be adjusted to suit the needs of vegetables by adding soil amendments and carrying out certain practices. As briefly mentioned in the introduction, organic gardening infers an interest in maintaining well-structured and fertile soil that will provide plants with nutrients, air and water. In contrast, many “modern” agricultural practices revolve around feeding the plant directly with soluble nutrients in synthetic chemical forms that are immediately available to plants. Such highly soluble chemicals are easily lost in water moving through the soil. Organic soil amendments and rock powders release nutrients slowly and maintain a high reserve of nutrients.

Many organic gardeners believe that amendments from off-farm sources should be minimized. This is often difficult for gardeners in non-farm communities. Consequently, the following description of soil amendments includes purchased as well as home-produced products.Organic matter is important in all soils because it improves both soil structure and fertility and feeds the soil life. It must be added regularly, as it continually decomposes. Organic matter plays a major role in improving soil structure. As it decomposes it releases “glues” that hold soil particles together, forming a crumb-like structure that allows for good drainage and aeration. In addition, the organic matter itself improves the nutrient and water-holding capacity of the soil. Consequently, organic matter should be added to excessively sandy soils to increase water- and nutrient-holding capacity, and to clay soils to make them more friable and to improve drainage and aeration by building structure.

Organic matter releases many plant nutrients as it decomposes, so it essentially is a fertilizer. Furthermore, it has a property that often is a very important advantage over purchased, synthetic fertilizers: It releases minerals slowly over a long period of time. This reduces leaching, decreases the risk of throwing the soil system out of balance and decreases the risk of “burning” the plant. (Some synthetic chemical fertilizers are so concentrated that they can kill, or “burn,” plant tissues. Some manures, applied to excess or when too fresh, can do the same.)

Here are some common sources of organic matter:

1. Farm manure is one of the best sources of organic matter and can supply the bulk of the fertilizer elements that vegetable gardens need. The general rate of application for cattle, hog or horse manure is 300 to 500 pounds per 1,000 square feet of garden. A simple way to estimate this is to apply a layer 2 to 4 inches thick on top of the soil and work it in to a 6-inch depth. Poultry, sheep, goat and rabbit manures should be applied at half this rate because of their higher nutrient content. If organic matter increases to more than 7 percent, avoid adding manure for a year or two.

If you are using cattle, hog or horse manure, work in rock phosphate as well at a rate of 4 to 5 pounds per 100 square feet (if your soil test indicates a need for phosphorus). Unless manure is well rotted, it should be applied before plowing, tilling or spading and then be turned under. Concentrated manure should not be piled around a plant as it may burn the plant.

2. Green manure: Organic matter levels can be maintained or increased in a soil by planting a green manure. Green manure is a crop grown with the intent of turning it under while it is still green. In addition to adding organic matter, green manure also returns nutrients accumulated in the plants to the soil. Legumes make particularly good green manure because they possess deep roots that draw up minerals from the subsoil. Also, they live symbiotically with bacteria that can incorporate atmospheric nitrogen that will also be released in the soil when the plant is turned under. Sow a green manure either as a winter cover crop or in a different portion of the garden each season. Some common green manures are: oats (planted in early fall for a winter cover or grown in the summer) and buckwheat or red clover (grown in summer). [See the MOFGA Fact Sheet, “Using Green Manures.”]

3. Compost is an excellent source of organic matter and nutrients. In its finished form it contains the major plant nutrients, nitrogen, phosphorus and potassium, as well as all the minor nutrients that plants need. Furthermore, it releases these nutrients slowly, thus minimizing runoff and leaching. A compost pile may be made of leaves, weeds, hay, manure, waste vegetable matter, coffee grounds—essentially any vegetable matter. Items to avoid because they decompose slowly and attract unwanted animals include meat, bones and fat.

Pile the vegetable matter in layers if possible: first an 8-inch layer of vegetable matter, then a 4-inch layer of manure, then a thin layer of soil, then repeat the layers. The pile needs to be quite large and built all at once before it will begin composting; 5 feet in diameter and 3 to 5 feet in height will be very good. Smaller piles and piles built bit by bit decompose and produce a fine soil amendment, but they do not heat enough to kill pathogens and weed seeds.

As you make the layers, water them. The pile should be kept moist but not wet. Turn the pile with a fork 10 days after you start it and again two or three weeks later. The compost is finished when it looks dark and decomposed and smells earthy. Good compost can be made in 6 months, but under less than ideal conditions, it may take a year.

For a good fertilizing program, add a layer of compost 1/2 to 1 inch thick to the top of the soil and work it in each spring. If your organic matter increases to over 7 percent, or if your phosphorus increases to more than 40 lb/A, avoid compost for a year or two. Soil tests will tell you if you need any other nutrients—you may not. (For details on fertility, see the MOFGA Fact Sheet, “An organic Farmers Guide to the Interpretation of a Standard Soil Test from The University of Maine.”) Some people grow good gardens using just compost for fertility, and research shows that this is possible. (For more details on Composting see the MOFGA Fact Sheet, “Composting in the Backyard or on a Small Farm.”)

Soil Amendments (rock powder and ashes): Lime is commonly used to adjust the pH of the soil. The symbol pH indicates the soil acidity or alkalinity, 7.0 being neutral, while above 7.0 is alkaline and below 7.0 is acid. Most vegetables grow best on a slightly acid soil—one with a pH between 6.5 and 7.0. Lime should be used on a garden only when a soil test shows that it is necessary. In Maine, most soils are acid unless lime has been added previously.

Soil test recommendations for liming are based not only on the pH, but also on the quantity of organic matter and clay. If no recommendations are available, you can follow these rough guidelines: If the pH is 5.5 to 6.0, use 3 pounds of ground limestone for each 100 square feet of garden on sandy soils and 5 pounds on heavy clay soils. Many soils in the Northeast are deficient in magnesium, especially after lime and potassium fertilizer have been added, so dolomite (high magnesium) limestone is recommended.

Wood ashes have two-thirds the effect on soil acidity as does lime and should not be applied in large quantities unless the soil is known to be acidic. If lime is needed, wood ashes are good because they also add potassium. Store the ashes in a covered container through the winter to keep them dry, because the potassium in them is very soluble.

Table I lists some other sources of nitrogen, phosphorus and potassium along with the percent analysis. Remember that nutrients in these materials are not immediately available. Furthermore, their release depends heavily on soil conditions in many cases. Consequently, deficiencies identified in soil tests are more difficult to remedy with organic and rock powder amendments than with synthetic fertilizers. Synthetic fertilizers allow a gardener to accurately match the quantity of available nutrients with the needs of a particular crop.

In contrast, the organic gardener has a goal of maintaining a balanced reservoir of nutrients in the soil that slowly becomes available to the plant. Building this reservoir takes time. Soil tests are important in order to quantify its development. They should be done each year for the first few years. Once good levels of nutrients are achieved, a test once every three years is fine. (See the MOFGA Fact Sheets, “An Organic Farmer’s Guide to Interpretation of Soil Tests” and “Natural Sources of Plant Nutrients” for more detailed information.)

II. Preparing the Soil and Planting

Adding Amendments and Turning the Soil. Slow release fertilizers such as lime or rock phosphate should be added in the fall as the soil is turned. However, lime and rock phosphate should not be applied together, because the calcium from the lime will slow or prevent the release of phosphorus from the rock powder. Ideally, you should get the pH up to at least 6.0, then have a soil test done to determine the phosphorus need. Sometimes, raising the pH will free enough phosphorus from its unavailable forms in the soil to satisfy crop needs. If you need phosphorus the following spring, bone meal may be a better source, because its phosphorus is more available than that in rock phosphate. Garden soils and the plants growing on top of them are turned over to incorporate the plant material into the soil and to loosen the soil so that vegetable crops will grow well in it. We do not recommend turning the soil in the fall unless a winter cover crop is planted after turning to prevent nutrient leaching and soil erosion, or unless the garden is mulched for the winter. Soils with good nutrient reservoirs are often better worked in the spring. If some nutrients are deficient, the soil may still be worked in the spring, but a quicker release is demanded from the fertilizer.

Do not work with soils that are too wet. A good test is to mold a handful of soil into a ball. If the ball is not sticky and crumbles readily when pressed with the thumb, the soil is ready to be worked. Working wet soil, especially with power equipment, destroys its structure and compacts it.

Some gardeners turn the soil only when they are first gardening on a particular spot. After that, if weeds are not a problem, they just push a garden fork into the soil and wiggle it back and forth a few inches to loosen the soil, rather than turning the soil over completely. This is easier on the gardener and may be easier on the soil life (although turning a green manure under can stimulate a great increase in soil life).

Planting. Draw a garden plan before planting. Include the locations of crops, length of rows, and spacing between rows. Locate tall vegetables at the north side of the garden so that they do not shade the short ones. Avoid planting crops that are susceptible to the same insects or diseases (crops from the same families; see Table II) near each other.

Crop rotation is important even in a small garden. Many plant pests overwinter in the soil and will build up from year to year if provided with a host each spring.

Furthermore, crops repeatedly planted in the same place deplete the soil of particular nutrients. Generally, crops in the same family should not be replanted in a garden space for two or three years. Ideally, gardeners should have two or more garden plots far apart from each other.

Most gardeners plant in rows in a flat garden, but some prepare raised beds. Such beds are either free-standing mounds of soil, 6 to 12 inches above ground level and 3 to 5 feet wide; or they are supported on the sides by wood, stone, concrete blocks or other materials. Supported beds can be much deeper than 6 to 12 inches. Beds offer excellent drainage and aeration, quick warming in the spring, and long-lasting soil structure, because the soil is never trampled. Furthermore, the soil can be amended much more efficiently, because it is in a confined space and amendments are not wasted on permanent walkways between the beds.

Compost, loamy soil, rotted manure and other amendments can be turned in each year, building up the bed. Weeds are also easier to control in this design, but quackgrass may creep under wooden sides. Because conditions are kept so close to ideal in the bed, one can garden much more intensively, i.e., place plants much closer together. On the other hand, close planting increases the chance of disease or insect spread.

Raised beds can dry out faster than level planting areas. If you have a very light, sandy soil, level gardens may be a better choice for you.

When to Plant. The garden can be planted over a period of three to four months. Some crops go in early because they tolerate cool, early spring weather, or they need cool weather, or they need long daylengths or a long growing season. Other plants cannot tolerate cool weather or late frosts and are planted later. Some long-season crops cannot tolerate frosts and need to be started indoors or purchased as seedlings and transplanted to the garden. Frost-sensitive plants should not be put out unprotected before the frost-free date. Table III lists planting dates according to the number of days before or after the frost-free date. To give you an idea of dates, in Greene, Maine, the mean last frost date in spring is around May 15, and the mean first frost date in fall is around September 15. If you are not sure when the frost dates are in your area, call your local Cooperative Extension.

Extending the Season. Two common methods of getting a little more out of the short growing season in Maine are: 1) starting plants indoors and 2) growing plants under protective cover outdoors during the early months. Certain vegetables suffer little from transplanting and can be started indoors in large flats, while others are quite sensitive and should be planted in individual containers in order to reduce root disturbance when they are transplanted. Many kinds of plants cannot withstand the stress of transplanting and should only be started directly from seed in the garden. (See Table IV.)

Extending the growing season with plant covers is very common in Maine. Hotcaps, empty plastic milk containers with their bottoms cut off and top left off, plastic row covers on wire hoops and polyester cloth row covers laid loosely over plants give a few degrees of frost protection and provide warmer conditions in the spring (especially the plastic). In addition, polyester cloth excludes harmful insects and is especially useful on the cole crops, onions and cucurbits (see below for details). For additional warmth, these season extenders can be used over black plastic mulch. All of these materials should allow air exchange to avoid overheating, so leave the caps off the milk containers and use slitted plastic row covers.

Transplants. Home gardeners are often advised to buy transplants from local supply stores. The most common problem with home-raised transplants is that they require at least four hours (and preferably six to eight hours) of direct sunlight or sufficient artificial light each day, otherwise they will be tall, spindly and susceptible to disease.

The advantages of home-raised transplants are that you get to choose from a great selection of varieties, and you can raise them free of fungicides, insecticides and synthetic fertilizers.

The key to raising satisfactory transplants, besides providing enough light, is fertile, disease-free soil mixtures. Artificial soil mixes are highly recommended, because they are less likely to harbor disease than mixes that contain soil, are lightweight and aerated, and hold water well. Such mixtures are available in garden stores. Artificial mixes need to have all nutrients added. Most store-bought mixes come with synthetic fertilizer added, but fertilizer-free mixes are available. Watering with manure or compost tea, or liquid fish or seaweed products once a week is a good substitute for synthetic fertilizers. Rock powders and most other organic fertilizers release nutrients too slowly for transplants. A mixture of equal parts soil, compost, vermiculite and peat will provide the nutrients, without supplements, for finished transplants raised up to eight weeks. (See the MOFGA Fact Sheet “Soil-less Mixes for Vegetable Seedling Production” for information on making your own mix.) This mixture could be “sterilized” by baking the soil and compost in an oven at 350o F for 45 minutes. All parts of the soil should reach 180o F and should stay at that temperature for 30 minutes. Overcooking or overheating releases toxic materials and kills helpful microorganisms.

Wet the mixture in a bucket. The peat in the mix may require a few hours to become wet; using hot water can hasten the wetting. After the mix is uniformly moist, put it into growing containers (flats, cells or individual containers). Plant extra seeds and thin out smaller or weakest looking seedlings, leaving one per cell or container. Warmth is very important for germination of many vegetables. (See Table V for recommended and minimum germination temperatures.) If your house is near the minimum temperature, provide supplemental heat (using a heating mat made for germinating seeds, for example). Excess watering may promote fungal diseases. However, once seedlings have a few true leaves, daily watering may be needed.

Plants grown indoors are sensitive to the outdoor conditions of wide fluctuations in temperatures, direct sunlight and wind. Thus, seedlings should be hardened off (acclimated) before they are set in the garden. Hardening off is best accomplished in a cold frame. A week or two before the date when the transplants can be safely set in the garden, slowly introduce them to direct sun and evening temperatures by putting them in a cold frame (or just outside, in a protected spot) first for an hour or two a day and then gradually extending the time until they are out all day. Watch their water needs and keep an eye on the cold frame to ensure that the plants don’t “bake” on sunny days.

III. Controlling Weeds and Preserving Soil Moisture Using Mulch

Weeds can be the gardener’s worst enemy. They compete for moisture and nutrients, offer a home for insects, harbor diseases and block the sun. Weeds can be controlled by hand weeding, cultivation and mulches. Most gardeners use a combination of all three. Shallow cultivation is less injurious to crop roots than deep cultivation and is just as effective. Hoe 1/2 to 1 inch deep; that’s all.

Mulch is material laid on the ground in order to shade out weeds and conserve moisture. Mulches may be either organic or plastic. Organic mulches are especially desirable, because they can be turned under in the fall or following spring and will add organic matter to the soil. Organic mulches are best applied after the soil has become warm and shortly after a heavy rain. Straw, old hay (watch for weed seeds), grass clippings, leaves, wood chips, newspaper and sawdust are common organic mulches. Cultivate before piling on the mulch, and pile it on thick enough (3 to 6 inches for hay, for example; or six sheets of newspaper covered with a few inches of hay to hold it down) to prevent the weeds from growing through.

Black plastic is very good at controlling weeds, conserving moisture and warming the soil. However, it does not decompose and needs to be picked up every fall. Because it warms the soil, black plastic frequently increases the yield of warm-season crops such as melons, peppers, eggplants and tomatoes. It is easier to lay the plastic before planting and plant through it than to lay it around plants. Lay the plastic and secure the edges with soil. Plastic is a nonrenewable resource and is a source of environmental pollution. It should not be an organic gardener’s first choice of mulch. (Biodegradable plastic mulches made from cornstarch are
available but are not approved for use in commercial organic production.)

IV. Individual Crops

BULBS: A bulb is a short stem with numerous fleshy leaves crowded together. Bulbs commonly grown in gardens include onions, leeks, garlic and shallots.

Onions

Soil Preparation. Onions do best on sandy loam that is rich in organic matter, but they can be grown on most soils. The recommended pH is 6.0 to 6.5. Onions are heavy feeders. A fertile soil should be prepared before planting by working in an inch-thick layer of a mixture of 8 parts compost or manure, 1 part wood ashes (if the pH is low) and 2 parts phosphate rock (if the soil needs phosphorus) to the top 6 inches of soil.

Propagation. The initiation of the onion bulb depends on day length. The varieties grown in Maine require 15 hours of daylight, so onions must be planted in early spring here so that they have grown enough leaves to bulb well once we reach 15-hour days. However, very early spring plantings are more susceptible to the onion root maggot. (See below.)

Most varieties require a long season, so seeds should be started indoors in mid-February to early March. While onion seedlings are growing indoors, keep them trimmed to 2 to 4 inches tall by giving them a “haircut” with scissors.

Onions can be grown from sets (small bulbs grown the previous year and available at farm supply stores), seedlings or seeds. Sow two to four seeds per inch, 1/4-inch deep. Plant transplants 1 inch apart. Sets larger than 1/2-inch in diameter are likely to go to seed before developing good bulbs. Plant sets 1 inch apart with the top sticking just above the soil surface.

Culture. Keep onions well watered; they grow best with an inch of water per week. They are poor competitors and need frequent weeding—and they are shallow-rooted, so don’t hoe deeply and don’t let weeds get too big before you pull them. For large bulbs, thin throughout the season to allow 4 inches on all sides of each onion. You can eat the thinned onions as scallions.

Common Problems. The onion root maggot fly lays her eggs in early spring and the maggots crawl down to cut the roots. A heavy infestation can destroy the whole crop. Infected onions will not store well, because fungi invade through holes on the bottom of the onion made by the maggot. The best protection is to cover the whole planting with a polyester row cover (such as Reemay). A mixture of ashes and rock phosphate laid at the soil line around the onion plants may prevent some infection. Beneficial nematodes are good for controlling root maggots; they are available through garden supply companies.

Harvest. For fall and winter storage, allow onion tops to fall over and turn brown. Knock down any that do not fall over with the mass. After the necks and tops look dry (about 10 days after knockdown), the onions can be harvested and stored in a cool, dry place. Do not store them in plastic bags; do allow for air movement.

Yield: 50 pounds per 50-foot row

Leeks

Soil Preparation. Fertilization requirements are similar to those for onions. Leeks should be planted in a trench about 6 inches deep. Gradually fill the trench during the growing season.

Propagation. Leeks are generally grown from transplants that are started indoors in February. Keep the seedlings trimmed to 4 to 6 inches tall until they are set in the garden in early spring.

Harvest and Storage. Leeks can be used throughout the season or harvested in the fall. Pack them in baskets and store them in the root cellar.

Garlic

Soil Preparation. Garlic grows best in well-aerated, deep, fertile soil with a pH of 6.5 to 6.7. Prepare the soil a few weeks in advance of the fall planting. Work in an inch-thick layer of rich compost or a well-rotted manure.

Propagation. Garlic is planted around the first week of October in central Maine. Break the head of garlic into individual cloves and plant each clove 2 to 4 inches deep, about 6 inches apart in rows that are about 12 inches apart. To protect the bulbs through the winter, cover the area with a 3- to 6-inch layer of mulch, such as straw or leaves.

Culture. In the spring, the garlic shoots will come up right through the mulch. Keep them evenly watered but be sure not to over-water. The ground should not be so wet or the drainage so poor that the roots are sitting in water. When the plants send up flower shoots, cut them off.

Harvest and Storage. Garlic is harvested in the summer. When the leaves start turning brown, it is almost harvest time. Garlic will store best if harvested when about half the leaves are brown, the cloves are softly bulging and the outer papery wrapper is starting to dry. Do not let the bulbs sit in the ground after they are ready to harvest or the cloves will start to break through their wrappers and they won’t store well. Pull up the bulbs when they are ready and let them cure for a few weeks in a dry, shady spot. Don’t wash them. When they are dry you can gently brush off the dirt. After curing, put the garlic in a cold, relatively dry place that never drops below freezing. Garlic stores very well through the whole winter.

Cole Crops

Interestingly, many of the common cole crops in your garden are the same species (Brassica oleracea). The variation in form that you see is the result of selection by agriculturists over hundreds of years. Some of the cole crops are grown for their leaves or buds (cabbage, Brussels sprouts, kale), others for immature flowers (broccoli and cauliflower) and some for their roots (rutabaga, turnip).

The cole crops are relatively resistant to cold and do well in cool climates. Broccoli and cauliflower produce much better heads in cool weather, and they should be planted to time their flowering with early summer (plant in early spring from transplants) or early fall (plant seed in the garden in late June or early July). You can have a supply of cabbage all summer by spring planting varieties with different maturing dates. Soil preparation, propagation and culture for all the cole crops are generally the same.

Soil Preparation. Cole crops do best on rich loams with good waterholding capacity. Crops can be grown on most soil types if water can be made available when needed. The recommended pH is 6.0 to 6.8. The cole crops are quite sensitive to low pH, and at pH above 7.2, a boron deficiency may develop, especially on cauliflower. Work manure, greensand and phosphate rock (if needed) into the soil before planting. If a soil test suggests a deficiency of boron, a dilute solution of household borax (0.1 pound/100 gallons of water) can be used as a foliar spray.

Propagation. For early spring transplants, sow cole crop seeds indoors about four weeks (six weeks for cauliflower) before you expect to set the plants out. Set out plants 12 to 18 inches apart in rows that are 2 to 5 feet apart. Cole crops are often set out without being hardened off in order to avoid a check in growth. (See “Problems.”) Plants are somewhat hardy and will take a slight frost, but a heavier frost may kill them. Cauliflower is the most sensitive. For a later crop, sow seeds in a seedbed in the garden in late spring or early summer. (See Table III.) After seedlings develop two true leaves, transplant them to rows and space them as above. Transplant on a cloudy day or in the evening, and water the transplants in.

Culture. Keep the soil evenly moist, avoiding long dry spells. Weed carefully, as the roots are shallow. A side-dressing of well-rotted manure or compost after plants have grown three or so weeks in the field is useful.

• Broccoli

Cut out large central heads when they are ready and before they start to grow loose. This will promote the growth of smaller side heads. Cabbage. Mature heads do not last long in the field: They will split as they become over-mature, especially after a rain. A slice with a spade that cuts off part of the root system may prevent splitting.

• Cauliflower

does not form good heads in warm weather; fall ripening is best. Cauliflower heads are kept white by blanching—tying the outside leaves together around the developing head when it is 2 to 3 inches in diameter. (Some newer varieties are self-blanching; their leaves grow around their heads naturally and do not have to be tied.) Harvest the heads when they are still compact and fairly smooth.

• Brussels sprouts

require a relatively long growing season. Sow seeds outdoors in a bed in mid-May and transplant plants 2 to 3 feet apart in rows 4 to 5 feet apart. They can be harvested over a long period. Pick as soon as they become firm, and the plant will continue to produce. The flavor is best after a hard frost or two.

• Kale

Sow seeds about 10 weeks before the first expected fall frost for a late crop. Kale must be well watered. Its best flavor occurs when leaves are firm, crisp and bright green. The leaves become tough and bitter as they turn dark green. The flavor is also best after frost, and kale can be harvested into the winter. If mulched or grown in a hoophouse or coldframe, it may resume growth for an early spring crop.

Yields per 50-foot row: broccoli—27 pounds; cabbage—75 pounds; cauliflower—30 pounds; Brussels sprouts—80 pounds.

Common Problems. Cabbage maggots (the larvae of a fly) will attack cole crops that are set out early. Symptoms are yellowing of the lower leaves, slow growth or wilting. Injury results from maggots feeding on root surfaces and tunneling through them. The adult fly looks a bit like a small housefly and lays eggs in April or early May on the base of the plant. The eggs hatch in a few days, and the maggots crawl into the soil. Cabbage, broccoli, cauliflower and radishes are favorites. The most effective control is covering plant rows with polyester cloth (floating row cover). Dusting the base of the plant with a mixture of rock phosphate and wood ash may prevent the maggots from crawling. Beneficial nematodes, available from certain garden supply companies, may work very well.

Imported cabbage worm and the cabbage looper are caterpillars that feed on cabbage and broccoli as well as some other garden plants. They are easily controlled by the microbial pesticide Bacillus thuringiensis (Bt).

Cutworms, the larvae of a night-flying moth, are a major problem, especially for transplants. Cutworms crawl along the surface of the soil at night and sever the plant right at the soil line. Some species climb up the plant and sever leaves. The best protection is to cut the bottom from a paper cup and slip the cup over the small plant, pressing it into the soil slightly, to form a barrier that cutworms can’t pass.

Legumes

Peas, dry beans and snap beans are popular garden vegetables that belong to the family of plants called legumes. Legumes produce their seeds inside a fruit called a pod. In some species the seed is the only edible portion, while in others the pod is edible as well. Peas are a cool weather crop, while beans need warm weather, especially for germination.

Soil preparation. Legumes possess the unusual ability to harbor symbiotic bacteria that fix atmospheric nitrogen into a form available to plants. Consequently, legumes require less soil nitrogen than other garden vegetables and may actually improve soil fertility as they grow and when the crop residue is turned under by adding nitrogen. (Most legumes grown in the garden will not add much nitrogen to the soil, since most of the “fixed” nitrogen is removed when the peas or beans are harvested.)Legumes require a well-drained soil, rich in organic matter, with a pH between 6.0 and 7.5. Work in rock phosphate (if needed) and wood ashes (but if the pH is high, use Sul Po Mag instead of wood ashes). In sandy soils that are low in organic matter, a small amount of nitrogen fertilizer will be necessary to get the plants started.

Propagation. Peas can be sown directly early in the spring after the soil temperature has reached 40 degrees F, although seeds that are not treated with a fungicide may show spotty germination. Better germination of untreated seeds will occur when the soil is 50 to 55 F. Inoculation with nitrogen fixing bacteria is beneficial, at least the first time the particular legume is grown in your garden. Innoculants come as a dry powder (available in most garden stores and seed catalogs). Wet the seeds and shake them around in the powder just before planting.

• Peas

can be planted in rows, but other methods have advantages. Tall varieties can be planted on both sides of a wire fence. Dwarf varieties can be planted in wide rows, since they do not suffer from some crowding. Leave about 2 inches on all sides of each seed. Midsummer plantings for a later crop of peas are possible but often give disappointing results because of the heat of summer.

• Beans

are sensitive to frost, and the seed will not germinate in cool soil. Soil temperatures should be at least 60 degrees F. Successive plantings every 10 days to two weeks until mid-July will ensure a steady supply. Sow seeds 1 to 1 1/2 inches apart in rows 2 to 2 1/2 feet apart; 3/4 inch deep in loam soils and 1 inch deep in sandy soils.

• Harvest

Peas are available as 1) edible pod varieties called snow peas in which the pod is harvested before the pea (the seed) develops; 2) snap peas, which offer both edible pods and peas; and 3) plain fresh peas in which only the pea is edible. The sweet flavor of peas is short-lived, so they should be harvested as soon as they become ripe.

Snap beans should be harvested when they reach full length and before the seeds begin to develop. Frequent harvest induces the plant to continue to produce new pods.

Dry beans (soy, kidney) are harvested after the pods are brown and dry or nearly so. Once the beans are air dried, they will store for years if kept cool and dry

Yields per 50-foot row: peas- 25 pounds; snap beans- 30 pounds.

Tomato Family (Solanaceae)

Tomatoes, peppers and eggplants are grown for their fruit and have similar cultural requirements. Potatoes are grown for their tubers, swollen portions of the underground stem, and will be treated separately.

Soil Preparation. A sandy loam that is well drained and contains a lot of organic matter is ideal. The pH should be 6 to 6.5. Well-rotted manure or compost and a handful each of rock phosphate (if needed) and greensand should be worked into the hole into which the transplants will go. Tomatoes are the heaviest feeders of the group. Too much nitrogen for any of these often leads to big, lush plants and delayed fruiting.

Propagation. These crops are sensitive to frost and require a long growing season. Normally tomatoes, peppers and eggplants are started indoors and are transplanted after the frost-free date. An early and midseason variety of tomato should be grown to have a supply from midsummer to fall. Tomatoes should be planted 2 to 3 feet apart in rows 4 to 5 feet apart. Peppers and eggplants can go 18 inches apart in rows 3 feet apart. If the transplants are tall and leggy, plant them 2 to 6 inches deeper in the soil than they were in the pot.

Culture. Peppers and eggplants need no staking, and tomatoes can grow with or without stakes. Staking keeps the fruit cleaner and helps avoid diseases. Plants can also be grown in wire cages. The crops benefit from mulch, but wait for the soil to warm or use black plastic. You can get a jump on the season by using black plastic mulch and row covers. Mulch can also help reduce diseases that otherwise splash onto plants from the soil during rains (see early blight below).

Yields per 50-foot row: eggplant—50 pounds; tomato—100 pounds; pepper—23 pounds

Common Problems. Fruit may not set or blossoms may drop if prolonged spells of cool nights occurred early in the season. Cold days and hot days (>90) prevent pollination, which, of course, prevents fruit development. The Colorado potato beetle will attack the whole family and is especially damaging to young eggplants. The best control in the garden is hand picking both adults and larvae and crushing the bright yellow egg masses. A natural-based insecticide called Monterey Garden Insect Spray helps control potato beetles. Row covers may also be used.

Early blight is a fungus infection of the leaves that may spread to the fruit. It is characterized by small, brown-yellow spots with concentric rings. The whole leaf will eventually turn brown and fall off the plant. Cool, humid conditions and shaded plantings promote the spread of the disease.

The fungus overwinters on plant debris, so compost plants at the end of the season and rotate the location of the tomatoes every few seasons. Do not plant tomatoes where other family members have just grown.

Cutworms can also be a problem in tomato plots. (See cole crop section.)

Potatoes

The edible part of the potato is a swollen food storage portion of the underground stem called a tuber. Short days, cool temperatures, low moisture and moderate fertility promote tuber development.

Soil Preparation. Potatoes are best grown in a moderately fertile soil that is high in phosphorus and potassium with at least moderate amounts of nitrogen available. Excess nitrogen will encourage too much foliage at the expense of tuber formation. Work in about an inch of compost along with phosphate rock (4 lbs per 100 square feet, if needed) and Sul Po Mag (1 lb per 100 square feet). Although potatoes grow best at a pH around 6.0, a pH higher than 5.7 promotes the fungal disease called scab. Manure applications should be made the fall before planting; otherwise they promote scab.

Propagation. Potatoes are grown from seed pieces, which are pieces of the potato tuber with buds (commonly called “eyes”) on them. Although you can use old potatoes for seed pieces, this is not recommended, because they commonly carry diseases. Do not plant grocery store potatoes, because, unless they are organic, they are commonly treated with anti-sprouting chemicals. Instead buy certified disease-free potato “seed” (actually tubers).

Cut the seed tubers into pieces about the size of a hen’s egg and be sure to have at least one to two eyes on each piece. Let the cut surfaces dry for a day or two, and then plant the seed 4 to 6 inches deep, about 10 inches apart, in rows that are 2 to 3 feet apart. For larger potatoes, space seed pieces 15 inches apart in rows.

Culture. When the plants are 4 to 6 inches high, soil should be hoed up around the plants to cover the stems. This prevents the tubers from being exposed to light and turning green and promotes more underground stem development. Plants should be watered during long dry spells to maintain even moisture during the season. Alternate dry and wet spells produce cavities in the tubers and knobby potatoes.

Yields per 50-foot row: 60 pounds.

Common Problems. Colorado potato beetle is the most prevalent insect. (See tomato family.) Flea beetles will attack young plants and, in large numbers, may destroy them, but are usually not severe. Excluding the insects with floating row covers is the best control. The potato leafhopper is a major problem some years. This is a tiny, flighty insect that sucks nutrition out of the plant. The leaves brown from the edges and often die from what looks like a disease. Scout early and through the season for the pest. Some varieties are much more resistant than others. For example, Norland is very attractive to them and Keuka is much less so.

Early and late blight are common fungal diseases that destroy potato foliage and infect the tubers. Late blight appears as brownblack areas on leaves and brown to purple discoloration on the skin of the tuber. Late blight was one of the causes of the Irish famine in the 19th century. The disease is carried through the winter on infected tubers. During the growing season, the spread of the disease depends on weather conditions. Spores are produced only in cool weather, below 60 degrees F, then invade new leaves when higher temperatures occur. A cool, wet July is often followed by blight in August and September. Some varieties (Kennebec, Essex, Cherokee, Sebago) are resistant to the common strain of blight, but not to some new strains. Copper may offer some control. If leaves become infected, delay digging tubers until a week after the first frost has killed the vines; otherwise the tubers will be infected by spores on the soil surface. Destroy infected tubers and, the following year, watch for and destroy any volunteer potatoes growing from the year before.

Harvest. Dig potatoes with a spade after the tops have turned brown. Cure them for about 10 days by storing them at room temperature in the dark, then store them in a cool (40o F), dark cellar.

Cucurbits

Cucumbers, melons, squashes and pumpkins, all vine crops, are grown for their fruit. They are warm-season crops that do poorly during cool summers and in the shade. They respond well to fertile soil, and under good conditions a few plants will supply a household.

Soil Preparation. A well-drained soil that is high in humus is best. Cucumbers, winter squash, melons and pumpkins do well when planted in hills. (A hill is not a mound of soil but a group of three to five plants.) Prepare the hill by digging a hole 10 to 12 inches deep and putting 1/2 to 1 cup of rock phosphate (if needed) and 4 or 5 cups of well-rotted manure in the bottom. Mix a cup of wood ashes with the soil from the hole and stir some of that mixture into the manure and phosphate. Then fill in the hole.

Propagation. Early cucumbers, muskmelons and watermelons are best grown from transplants started indoors four weeks before the last spring frost. Main season cucumbers, squash and pumpkins are generally direct-seeded outdoors. Some gardeners transplant their vine crop seedlings and direct seed cucumbers, squash and pumpkins on the same day to ensure a longer harvest season. Space hills 3 to 5 feet apart. Seed will not germinate in cool soil, so wait until it reaches 60 to 65 o F. This group benefits from warm soil and even moisture and does well planted through black plastic. Put the plastic on the soil a week or two before planting to help warm the soil.

Culture. If you did not use plastic mulch, apply a heavy organic mulch around the plants after the soil has warmed. Even moisture is essential. Sidedressing with well-rotted manure about 4 weeks after transplanting is beneficial. Cucurbits are not self-pollinating and require bees for pollination.

Yields per 50-foot row: cucumbers—45 pounds; muskmelons—40 pounds; summer squash—60 pounds; winter squash—80 pounds.

Common Problems. The striped cucumber beetle is the worst enemy. Not only does it destroy leaves and sometimes fruit, but it also carries an incurable disease called bacterial wilt. Large transplants are much more tolerant than tiny seedlings germinating in the garden. Covering a plant with a polyester row cover such as Reemay is a good solution, but be sure to remove the row cover once the plants flower so that bees can pollinate the flowers. Pyrethrum applied once a week is harsh but offers some control in serious infestations. Growing robust plants in healthy soil seems to help minimize cucumber beetle damage.

Harvest. Cucumbers and summer squash should be harvested when small because they lose flavor and texture when large. Keep them harvested, since ripening fruit draws energy from the plant at the expense of other, developing fruit. Winter squash should be allowed to mature to the point where the skin resists puncture by your fingernail. Store winter squash at room temperature in a dry place.

Root Crops

A diverse group, these plants are all grown for their enlarged, fleshy roots, thrive in cool weather and can be planted early in the spring. Many of these crops can be mulched and harvested well into the winter. Most are biennials and will produce flowers early in their second year. They include beets, carrots, radishes and parsnips.

Soil Preparation. Light, moderately fertile soil with good water holding capacity is best. Never add fresh manure, since excess soil nitrogen will promote hairy roots. The pH should be 6.5, and the soil should have plenty of potassium, so wood ashes are often appropriate. Dig the soil deeply and remove small rocks, since they will impede growth and lead to misshapen roots.

Propagation. Radishes germinate very quickly and mature in three to six weeks. Carrots and parsnips germinate slowly, and the soil must be kept moist during germination. Some gardeners sow quickly-germinating radishes in with carrots and parsnips in order to mark the rows before the carrots and parsnips germinate. All of these root crops are difficult to space correctly at planting and need to be thinned to allow large root development.

Culture. Weeding is essential. Carrots, parsnips and beets are slow to get started and are easily out-competed by weeds. Water during dry spells.

Harvest. Harvest when the roots are large enough to eat, since old roots lose their flavor and crack. Parsnip flavor is enhanced by frost, and some say the best crop is harvested the spring following the planting year. A thick mulch of hay will protect the roots, and they can be pulled through the snow until the ground freezes. Carrots can also be kept and harvested throughout the winter under a thick mulch of hay, but when Jean tried to do this, rodents ate her carrots.

Yields per 50-foot row: beets—35 pounds; carrots—45 pounds; parsnips—50 pounds; radishes—40 dozen.

Sweet Corn

Although sweet corn takes a great deal of space, it should be grown in any garden that has room, because peak quality occurs right after picking. Some gardeners say to get the water boiling before you walk out to the garden to harvest the corn. Many newer varieties of sweet corn hold their sweetness longer than older varieties.

Soil Preparation. Corn is a very heavy feeder and requires full sunlight. Fertilize the soil before planting, because once stunted, corn rarely recovers. Work a 2-inch-deep layer of well-rotted manure, 5 pounds per 100 square feet of phosphate rock phosphate (and 5 pounds per 100 square feet of greensand into the soil. Soil tests will indicate if less rock powder is needed in future years. A pH of 6.0 to 6.8 is recommended.

Propagation. Corn is planted directly in the garden, 6 inches apart in rows that are 3 feet apart. Thin plants to 12 to 15 inches apart. A supply of fresh corn can be obtained by following this schedule: Plant an early variety and midseason variety about two weeks before the last frost. When the early variety has produced four leaves, sow another planting of the midseason variety plus a late season variety. One week later plant some more late-season corn. For an extra-early harvest, some people also start corn seedlings indoors about two weeks ahead of time and transplant those seedlings at the same time that they direct seed their first crop.

Corn is wind pollinated, and pollen released from the tassel must land on every strand of silk in order to pollinate every kernel in the ear and avoid “skips.” So corn is best planted in blocks of at least four rows to ensure good pollination.

Culture. Corn is a heavy feeder, so prepare a fertile soil as noted under “Soil Preparation.” Sidedress with some manure when plants are 5 to 6 inches tall. Early weeding is essential. Hilling soil around the base of plants will keep down weeds and offer additional support. After the tassels are produced, corn needs 1 inch of water per week. Do not remove suckers (side stalks growing out from the base of plants), as this may injure the plants.

Yields per 50-foot row: 5 dozen ears.

Common Problems. Corn earworms and the European corn borer are the most common pests during the midsummer. The earworm does not overwinter in Maine, but adults migrate from the South by midsummer. The female moth lays eggs on the silk, and the larvae work their way to the tip of the ear and devour the kernels. Corn varieties with tight husks are more resistant. A few drops of mineral oil squirted into the ear through the silk channel may suffocate the worm. Bt squirted in the channel may work, especially with the oil. Johnny’s sells a tool called the Zea-later for applying this mixture. At harvest, gardeners can also simply break off the tips of ears of corn that have earworms.

The borer overwinters in debris from the previous year’s corn, especially the lower end of the stalk. Destroying the stalks, fall plowing, a cold winter, or early spring plowing will reduce populations. Early signs of damage appear as shot holes in the young leaves as they unfold out of the whorl where the caterpillar is feeding. As the caterpillar grows it will bore into the stalk and you can find holes where it enters or broken tassels where the stalk is weakened. Bt will work on the young larvae if you can get it down into the whorl at the right time. A granular Bt product is on the market, but the best controls are crop rotation and destroying last year’s stalks, unless you are surrounded by other fields of corn.

Photos by the authors

Last Published April 2009

The post Basics of Organic Vegetable Gardening appeared first on Maine Organic Farmers and Gardeners.

Ridge tillage as we practice it at Hackmatack Farm is a system of growing vegetable crops in raised ridges formed before planting. Essential to this system is incorporation of winterkilled cover crops and other organic matter into the top surface layer of soil as we form the ridges. Practically speaking, our crops grow on a single-row raised bed.(Photos 1 and 2)

Ridge tillage, in essence a hybrid between raised bed production and single row cropping, offers many of the benefits and advantages of both. With the added component of full-year cover cropping (a field is taken out of vegetable production every second or third year), this system creates soil conditions that favor proper air movement, water movement and residue decay, minimize soil damage or loss, break weed cycles and deplete the weed seed bank, and demand relatively low-intensive management by the farmer.

We designed our system focused on the soil and tillage, as a whole farm system – all other systems for our vegetable crop production (weed control, pest control, fertility, irrigation, labor, etc.) fall under and within the overall scheme of our ridge tillage system. It is a reduced or minimal tillage system in which we use a 32 hp tractor and three basic tillage tools. Once every third year (at the beginning of the cover crop year), we plow with a moldboard plow. We use a disc harrow to prep and cover and eventually turn in cover crop plantings (three per year); we also use the disc harrow to clean up vegetable rows after harvest. The main tool, however, is our ridge-former tool – simply a 3-point-hitch double tool bar with assorted discs and sweeps mounted on it. (Photo 3) We use this once every spring to form the vegetable ridges (Photo 4) and two or three times in early summer to cultivate established crops. We also set this tool bar up with three large shanks for occasional deep ripping if needed or desired.

Photo 1 – The ridge tillage system used at Hackmatack Farm essentially means we grow crops in single-row raised beds.

Photo 2 – Onions in July.

Photo 3 – Forming ridges in the spring.

Photo 4 – Formed ridges warming in spring.

Going into our eighth year of this system (and our 18th year of MOFGA certified organic vegetable production on most of our fields),we are maintaining levels of organic matter in the 8.0 to 8.9 percent range on our very stony glacial till loam. In 2013, we grossed the equivalent of $40,000 per acre for our vegetable operation, averaging $2.51 per row foot.We are adding only small amounts of compost, manure or other off-farm inputs (straw,seaweed,rock powders,fish meal) and practice a high-residue cover cropping plan.

The typical cover crop or fallow year starts with a planting of oats and peas in spring, followed by buckwheat in midsummer, and by oats, peas and barley in late summer to be winterkilled. We often incorporate compost or manure in this year. Two years in vegetables follow the cover crop year, with different crop families being easily mapped within the ridge system so that no section of field grows the same vegetable family for a minimum of five years, often longer.

We form ridges early in spring, as soon as the ground can be worked, incorporating the winter-killed cover crop into the ridges. In our system,we form two ridges between the tractor tires (set 52 inches apart),so the ridges end up being 26 inches center-to-center.When first formed, our ridges are typically 12 to 14 inches high; after planting and cultivating throughout a season,they end up around 9 inches high.

To plant,we scalp the crest of the ridge with a rake, incorporate soil amendments with a narrow cultivating scratcher, and then smooth the seedbed with the rake.We use an Earthway seeder for most direct-seeded crops, or transplant into the scalped and prepared ridge

Figure 1 – Depending on the crop, either one, two or
three rows are planted down each ridge.

Depending on the crop,we plant either one,two or three rows down each ridge.(Figure 1) Crops for single-row planting include onions,scallions,shallots, leeks, garlic, chard,spinach, beans and head lettuce.Crops planted in double rows include radish,summer turnip, baby bok choi, parsley and cilantro.We use triple-row plantings for arugula, mesclun and lettuce mixes, and carrots.

Certain crops require a wider “bed,” and for these we instigate a “doubled-ridge” formation. We set the outer discs of the tool bar slightly closer together and remove the inner discs and sweep, creating a bed about 40 inches wide with a shallow valley down its center. We apply soil amendments into the valley, cover the bed with 48-inch-wide black plastic mulch, and then transplant tomatoes, zucchini, cucumbers and melons down the center valley.We plant potatoes the same way, but without black plastic, and hill them with discs on the tool bar.

We use the same 3-point-hitch toolbar in differing configurations to cultivate most crops until they are too tall for our tractor.Typically our quick-growing greens,such as mesclun, arugula,summer turnip, etc., don’t require cultivation; many crops (chard, beans, head lettuce, onion family) require one or two tractor cultivations followed by either straw mulch in the narrow pathways or quick hand-hoeing for weed control for the rest of the growing season.The slopes of the ridges are well suited for ease of cultivation, allowing discs to throw more soil up onto the side of the ridge or,with very shallow hoeing (we use a collinear hoe),readily allowing soil to shift and weeds to fall into the pathway between ridges.

The expanded spacing provided by the bio-extensive system in concert with favorable air and water flow through the soil provided by the high-residue cover cropping minimizes irrigation needs.When we do need or want to water,we move hoses and sprinklers into the field.Good airflow above ground, in and around the crop, also naturally provided in this system, helps minimize or mitigate disease pressure.

Figure 2 – Ridge tillage, at the bottom of the figure, creates a greater
area of topsoil and biotic root zone than raised or level beds.

Ridge tillage significantly impacts the soil ecosystem by arranging topsoil in a way that enlarges and optimizes the volume most used by plant roots and the diverse ecology of microorganisms that promote plant growth and health. Figure 2 shows three cross-sectional views of different vegetable bed configurations.View 1 at the top shows an old-fashioned,flat field row cropping,with 52 inches of soil to use between the tractor tires or pathways.View 2 shows a typical 48-inch-wide (at the base) raised bed,which, at 9 inches tall, measures 59 inches along the soil surface,from side to side between the same tractor tires.View 3, our ridge tillage system,shows two raised ridges, each 9 inches tall,which together measure 68 inches along the soil surface from side to side – 30 percent more than the flat field and 15 percent more than the typical raised bed.

This expanded surface area of soil is highly beneficial.The top 3 inches of a vegetable field or garden soil, especially in a high-residue system, is where most of the macro and microorganisms live,so ridge tillage expands and increases this “bioactive zone.”

Transitional or edge ecologies,such as at the forest’s edge or the ocean shore, are highly biotic zones where many forms of life thrive and biological activity is greater than in other, non-transitional ecosystems. In our vegetable fields,simply creating ridge formations expands this biotic zone along the surface of the topsoil (and the biotic root zone just under the soil surface).

Moreover,the physical shape of the field that our ridge tillage system creates actually enhances the positive impacts and mitigates the negative impacts of natural forces such as sun, wind and rain. Figure 3 illustrates the benefits of all these tiny mountains and valleys created in the vegetable field.

Figure 3 – The many small mountains and valleys in a ridge tillage system create
warmer soil earlier and minimize wind and water erosion.

Such a system is highly adaptable to varying equipment and labor needs,soil types and farming preferences.We designed and chose this system for several personal reasons:

• We wanted to minimize labor requirements for our vegetable operation, with little or no dependence on off-farm hired or apprentice help.We cultivate about 1 1/2 acres for vegetables, with the equivalent of one full-time person May through August, one part-time person March through October, and one hired part-time employee for July and August.Our certified organic wild blueberry operation requires up to a dozen employees,so our time, especially in August, is precious and we needed a vegetable production system that did not require large amounts of time and management.
• We wanted to minimize costs of capital equipment. It was important to strike a balance between mechanization and reliance on lots of different, costly equipment.We wanted low-tech, multi-purpose equipment with minimal investment.One tractor with one adaptable tool is at the heart of our system.
• We wanted to minimize tillage and improve soil structure. Before 2006, we had been using a BCS rototiller on a 42-inchwide raised bed system and saw diminishing tilth and air and water flow through the soil with increasing weed and disease problems. All that has now been reversed.
• We wanted to minimize input costs and reliance on off-farm purchases for fertility,soil-building and crop growing. Biointensive raised bed systems require high levels of fertility and greater irrigation; our bio-extensive system, using more space more wisely, improves soil and soil-life conditions with fewer inputs.

Our ridge tillage system uses relatively low-cost equipment, low intensity of inputs, and low labor demands. Properly incorporated cover crop residue allows plants to use more of the top 3 inches of soil (the bioactive zone) compared with flat row cropping and raised beds, and it simplifies management of soil air and water as it improves aeration and water flow/capillary action within the soil – all with fewer passes and less tillage compared with the other systems. It works with low power and low-tech cultivators (of which many options/types will work, including more expensive and refined planting and cultivating equipment) and is adaptable to almost any soil type (clay,sand, loam, etc.) or primary power source (horse or tractor).

Farming in the face of global climate change, we are impressed with the resiliency of our fields after extreme weather events, whether heavy rain, wind, drought, unseasonable high or low temperatures, etc.The soil on the ridges dries and warms earlier and more evenly in spring and recovers more readily after a heavy storm or odd weather pattern during the growing season.

Do I advocate for more farmers to use ridge tillage? You bet.

About the author: Nicolas Lindholm and Ruth Fiske raise MOFGA certified organic produce at their Hackmatack Farm in Penobscot,Maine, selling it primarily through farmers’ markets in Stonington,Deer Isle and Castine, as well as to the Blue Hill Coop and a few other select markets in the Blue Hill area. Nicolas also volunteers his time on MOFGA’s agricultural services committee

MOFGA has a two-row ridge-till toolbar modeled after Nicolas’ equipment in the shared-use farm equipment program hosted in Unity. This toolbar is easily adaptable to a variety of situations and is intended to give growers an idea of how this system might work on their farm. Visit our Shared Use Farm Equipment Page to learn more. This work was supported by the Natural Resources Conservation Service, U.S.Department of Agriculture, under agreement number 69-1218-2-24.

The post Ridge Tillage at Hackmatack Farm appeared first on Maine Organic Farmers and Gardeners.

By Eric Sideman, Ph.D.

The causes of some garden tragedies are obvious, while other causes are mysterious. When Colorado potato beetles eat every leaf and your potatoes never get larger than golf balls, there really is no puzzle to solve. But sometimes gardeners don’t know what went wrong, and they chalk some problems up to a bad season, when a tiny insect or hidden disease actually caused the problems. You can’t do anything about crop failures in New England in September, but the following clues to and remedies for common problems should help next year.

Tarnished plant bug. Length 1/4 inch. Illustration from Handbook of the Insect World, University of Kentucky College of Agriculture, Cooperative Extension Service.

Onion thrip. Illustration from Insects and Diseases of Vegetables in the Home Garden, USDA Agricultural Information Bulletin No. 380, Superintendent of Documents, U.S. Government Printing Office, Washington D.C. 20402. 1980.

Seed corn maggot. Illustration from “Corn Insects – Below Ground,” Picture Sheet No. 5, USDA.

Potato leafhopper. Length 1/8 inch. Illustration from Handbook of the Insect World, University of Kentucky College of Agriculture, Cooperative Extension Service.

Blossom-end rot of tomato. Photo from Insects and Diseases of Vegetables in the Home Garden, USDA Agricultural Information Bulletin No. 380, Superintendent of Documents, U.S. Government Printing Office, Washington D.C. 20402. 1980.

Peppers and Eggplants

I commonly hear about big beautiful plants and no fruit, and the most common guess at the cause is excess nitrogen. While that could be the cause, too much nitrogen is not a common problem for organic gardeners, except for those using excess blood meal. Two more common causes for delaying that first bowl of salsa because of lack of jalapenos are weather and insect attack. Hot days early in the season are uncommon, and when they do occur you can’t do anything about them, but temperatures above 90 can prevent pollination and fruit set.

Blossom drop due to feeding by the tarnished plant bug (TPB) is even more common in some places. These little sucking insects attack the buds, which drop off without developing into fruit. If you have big, beautiful pepper or eggplant plants and lots of buds and still no fruit, think tarnished plant bug. This very common pest feeds on about 300 species of plants and many crops, so crop rotation will do nothing. The worst case occurs when a nearby field of alfalfa is mowed when your pepper crop is budding, and the TPBs rush to your peppers. To prevent this problem, cover your peppers and eggplants early next season with a floating row cover at least until the flowers open. This makes sense anyway, because these crops do not like those chilly, early June nights in Maine.

Onions

Do you have big, beautiful onion plants until about halfway through the summer, then have the onions turn yellow early, fall over and leave you with onions that are smaller than radishes? This could be due to drought, lack of nitrogen or botrytis, but have you ever looked for thrips? Thrips are tiny (about one millimeter long, and slender) and they hide near the base of the plant between the leaves that are close together. The best way to sample for thrips is to harvest some plants, remove all the leaves and shake them over a suitable surface. As few as five thrips per plant per season affect yield. Thrips do the most damage in hot, dry summers. Cultural controls can reduce the damage significantly. Onion thrips overwinter in onions and other hosts (especially alfalfa, but to some extent many garden crops, such as cucumber, pea, pepper and squash). Volunteer onions are often the source of the initial infestation in the spring, so fall sanitation is important if thrips have been a problem. Heavy overhead irrigation will reduce thrips populations, often eliminating the need for chemical control. If sprays are needed, the new, organic formulation of spinosad (Entrust) is said to work well.

Corn and Beans

Very spotty stands of corn are often blamed on the seed but usually are due to crows or the seed corn maggot. Crows will even go after seed after it sprouts and the plants are an inch tall. Sometimes you can find the little sprouts lying on the ground, with the seed gone. Silvery scare tape is said to work, as is a string tied a few inches above each row. I cover my corn with a 30-foot-wide row cover, so I have not tested scare tape or string.

The seed corn maggot is not so obvious. This fly larva, or maggot, feeds on corn or bean seeds and is a common problem for people like me who strive for the first corn on the block. In cold soil, especially when the weather is cold and damp too, the seeds germinate very slowly, giving the fly’s egg time to hatch and the larvae a chance to attack. If you do not see germination in the expected time, check the seeds for maggots. If they have eaten the seed, you can replant. The only sure-fire protection is to wait for the soil to warm before planting these crops so that they germinate quickly. Of course, I don’t take that advice but take my chances every year, planting corn and beans on May 15th. Transplants work well for avoiding seed corn maggot; I put out two-week-old transplants on May 15 under a floating row cover.

Potatoes

When folks ask me what organic potato growers use to top-kill their plants before the fall harvest, I joke that organic growers rarely have live potato plants then. While this is only a joke, many potato growers do have a problem with potatoes dying early – for a number of reasons. The most common is feeding by the potato leafhopper. The initial damage consists of yellowing of the tips and edges of the leaflets. Gradually the leaflets curl up and inward, and the edges die and turn brown, resulting in what is called “hopper burn.”

Potato leafhoppers do not overwinter in temperate climates. Each year they spread north on winds out of the Gulf area. Some leafhoppers are almost always around during the growing season, but only some years are the numbers high enough to cause hopper burn and early death of whole plantings of potatoes (and beans). No cultural practices have proven effective in controlling the hopper. Varietal resistance does seem to occur but has not been substantiated yet.

To confirm that leafhoppers are numerous, brush your hand over the tops of the rows and see if lots of them fly up. Rotenone has no effect on this insect, but pyrethrum does.

Blossom-End Rot of Tomato and Summer Squash

Everything seemed to be going fine until just before the fruit ripened, then you noticed the end of the fruit where the flower was attached was turning brown and rotting. This is a noninfectious disease, i.e., no pathogen causes it. Instead, it is caused by calcium deficiency in the fruit, which is usually associated with drought or poor water management in irrigated plots. Calcium is not very mobile in the plant, so during times of water stress, the fast growing regions of the plant suffer. Providing uniform moisture will usually prevent the problem. Supplemental calcium may be needed, but rarely.

Lettuce

Sometimes aster yellows affects only one or two plants, other times it can take down the whole crop. The first symptoms are chlorotic center leaves that fail to develop normally, remaining short and stubby or twisted. Light brown latex deposits on the underside of the midribs are diagnostic. Aster yellows is caused by an unusual, mycoplasma-like organism. These prokaryotic cells inhabit the phloem (food conducting cells) of lettuce and are transmitted from plant to plant by the aster leafhoppers in which they can live and multiply. The pathogen survives the winter in perennial weeds and crops and is picked up by the aster leafhopper in the spring. If aster yellows was a problem, control perennial weeds in the field margins and do not mow crops such as clover when lettuce is young.

Eric Sideman is MOFGA’s director of technical services. You can contact him at the MOFGA office or at esideman@mofga.org with your questions about organic growing.

The post Whodunits appeared first on Maine Organic Farmers and Gardeners.