Farming the Shoulder Seasons

Spring 2017
At the Farmer to Farmer Conference, Eliot Coleman (left) and Patrice Gros talked about growing crops during the shoulder seasons of the main growing season. English photo

At MOFGA’s 2016 Farmer to Farmer Conference, Eliot Coleman of Four Season Farm in Harborside, Maine, and Patrice Gros of Foundation Farm near Fayetteville, Arkansas, discussed growing and marketing crops during the shoulder seasons to close the gaps on either end of the traditional growing season.

Four Season Farm

Coleman said that one key for success in the fall-into-winter season is getting plants established before days are shorter than 10 hours – November 5 at the 44th-parallel farm that he and Barbara Damrosch own.

“It’s almost like somebody pulled a switch,” said Coleman. “It’s just amazing how that slows growth if you plant seeds after that date. If you plant them before that and the plants have begun to establish root systems, they can keep producing further.”

To grow well in the shoulder seasons, he said, track the planting date and whether that crop was too early or late. He provided a handout of planting and harvest dates for fresh crops growing outdoors for fall harvest, for winter harvest in an unheated greenhouse and in a cool house (kept above freezing), for storage crops in a root cellar and in an outbuilding kept at 55 F and 60 to 70 percent relative humidity [Four Season Farm_Winter Crop Planting.pdf]

Coleman and Damrosch also freeze paste tomatoes for winter use and sales. According to Coleman’s handout, “We freeze bags of as-harvested paste tomatoes without any processing. To use, hold tomato under warm running water for two seconds to remove skin. Place in colander to thaw. Use the clear liquid that runs off in soups. Use the flesh for an incredibly fresh tasting tomato paste. We sell bags of these frozen tomatoes at our winter markets.”

Two years ago Four Season Farm operated year-round and grossed $165,000 in sales from 1-1/2 acres, with seven employees, three farmers’ markets and a farm stand. They also make a few sales in September to stores and restaurants. After dropping the farmers’ markets, closing the farm stand (although it may open it for a couple of months next summer) and focusing on selling from October to June, the gross dropped to $100,000, but the net increased from $30,000 to $60,000. “Succession planting and attention to detail are keys,” said Coleman.

Now that Four Season is growing less, 3/4 acre is rotated to a grass-legume mix where laying hens graze, and their feed becomes fertilizer, which the hens spread. Rotating with a grass-legume mix sometimes produces a 50 percent yield increase. Coleman thinks that the fibrous roots of grasses are one of the best sources of soil organic matter as they decompose in place. That’s why we love moveable greenhouses,” he said.

Regarding leeks, “We knew it was hard to protect them over winter,” said Coleman, “because we were supposed to plant them far enough apart to get in with the tractor and hill them to blanch the shank at the bottom. We learned from friends in Europe that if you made a 9-inch-deep hole with a long dibble and grew 10-inch-tall seedlings, [you could] drop them into the hole. We never put any soil in; it just falls in when we cultivate or irrigate. It works. So now we have enough leeks in a small area that we can afford to cover them. They’re hardy until Christmas and then will go all winter if they have a low tunnel or greenhouse … Even if you don’t sell them in the winter, they’re there to be sold in March and April.” Using materials from the Home Depot plumbing department, Coleman fashioned a tool to make a 9-inch-deep, 1-inch-diameter hole for leek seedlings.

The tool also makes holes to hold Quick Hoops. Coleman grows crops in 30-inch-wide beds with a 1-foot path between them, so a 6-foot-diameter hoop covers two beds. He’s been able to overwinter onions under Quick Hoops covered with row cover and a sheet of solid plastic. His winter tunnels run north-south to minimize the opportunity for prevailing winds in his area to loosen the plastic held down by sand bags. Covering an area with Quick Hoops costs about 5 percent as much as a greenhouse, “so you can cover shoulder season crops with very inexpensive technology.” He originally used glass-covered cold frames for winter harvests. “It’s surprising how productive you can be through the winter just with cold frames,” he said.

Previously the systems used to move greenhouses at Four Season Farm were expensive. Now these farmers use a simple modular greenhouse, with 12-foot-wide, 10-foot-long sections made from electrical metallic tube (EMT) conduit covered with plastic, and with scissor doors. With the plastic removed, individual units are easily moved. For example, after Thanksgiving they move a greenhouse that had covered spinach so that it then covers leeks.

Asked about voles, Coleman said, “They are the pest of the shoulder season.” He used to make 12-inch x 8-inch x 6-inch-tall wooden boxes with removable tops, drilling a 1-1/2-inch hole at each end to mimic a mouse-chewed hole, because voles want to scurry into small dark holes. He put traps in these boxes and placed them throughout fields among susceptible crops. At first he baited the boxes, but the voles soon learned that the smell of bait “meant something bad.” Without bait, a vole enters the box, which then smells like vole and attracts other voles.

He now uses dark green 9-inch x 4-inch ammunition boxes with removable tops. “We drill 1 1/2-inch holes at each end and put a trap in,” said Coleman. “We also glue a little flag to them so that we can find them in the field.” About a dozen traps cover a field of about 600 square feet.

Every morning Coleman throws recently deceased voles over the deer fence, where a local fox soon comes by to eat them.

A weasel that got into one greenhouse was “probably the best vole control” Coleman has seen.

Coleman forces endive in plug trays covered with a black plastic bag. English photo

Asked about managing water during freezing temperatures, Coleman said they have no-freeze hydrants, which don’t have to be in or near the greenhouse. When they are turned off, water in the shaft drains down to 4 feet below ground and won’t freeze. He keeps hoses in one section of a greenhouse all winter. To irrigate in an unheated house, they thaw the hose and plug it into overhead sprinklers. They rarely irrigate from November 15 to February 1, however. They do irrigate when they sow carrots in one house after harvesting leeks. “On New Year’s Day,” said Coleman, “traditionally we’re planting a bed of carrots in that greenhouse – and selling them on May 10. They are under a second layer of fabric in the greenhouse … I make sure every couple of days I can turn on the overhead sprinklers or go out with a watering can to keep carrot seeds moist until they come up.”

Asked about other insect pests, he said that aphids used to appear in mid-February every year on overwintered spinach in unheated houses. Washing spinach removed the aphids but did not remove the “mud igloos” that aphid parasites made. Coleman learned that aphids occur when soil is high in nitrogen. By mid-February, with no irrigation, the greenhouse soil had accumulated nitrogen. Now he starts irrigating the spinach houses in mid-January, even though the soil is not dry, to limit aphid populations.

Four Season Farm has two greenhouses where tomatoes, peppers and eggplants grow in summer. Every other year one gets solarized in July by irrigating the soil, spreading plastic over the soil and sealing the edges, and letting the soil temperature at 2 inches of depth reach 145 F. That kills all weed seeds, and because their soil tilther goes only 2 inches deep at most, they do not bring up more weed seeds. Most researchers, said Coleman, are interested in killing verticillium and other diseases with solarization.

Because thrips can overwinter and infect seedlings the following spring in a greenhouse where onions were dried the previous summer, Coleman plans to steam clean that greenhouse in midwinter with an electric-powered steam cleaner.

Coleman had one final tip – for growing witloof chicory. “We cut Belgian endive roots to 7 inches at harvest in late October and set them upright in the same grooved plug trays we use for starting our sweet potato plants. Each tray is placed in an 8-inch-tall bulb tray and stored in the root cellar. For sprouting we place them in a tub with 4 inches of water, cover with a heavy-duty black plastic garbage bag to exclude light, and place on a heating pad at 55 F until they are ready.”

Foundation Farm

Patrice Gros of certified organic Foundation Farm in Northwest Arkansas, near Fayetteville, showed detailed tables and graphs of his shoulder-season production system. (See “Permanent Raised Beds” in this issue of The MOF&G to learn about his cultural practices and labor requirements.)

Gros said that about 13 years ago he considered extending the harvest into winter – a traditional resting time – at his zone 6a farm, where outdoor winter temperatures range from 0 to -5 F a couple of nights each winter, and up to 10 to 20 F. When he started winter growing, “It was like falling in love again with the same passion” as he learned new ways to grow plants under different light and temperature regimes. He now sells at two winter farmers’ markets and has additional summer markets. He finds that starting trays for winter on August 1 is the most difficult part of winter farming. “It’s hard psychologically to think winter farming in [the heat of the] first week of August.

“I take pride in not wanting to get bigger,” said Gros. Last year he grossed about $80,000 on half an acre (square footage of cultivated area). His annual profit is about $65,000 to $70,000.

Weekly sales charts from 2015 and 2016 show that Gros sells every week of the year, making $500 to $700 in the first week of January. Much of his income is still in summer and, even more, in September and October, when soil biology peaks.

His season extension involves medium-grade row covers (sometimes doubled for protection down to 20 F; and held in place with 5-foot-long 1/2-inch rebar rather than sand bags), three low tunnels and two high tunnels. He noted that row covers and tunnels also protect against such predators as crows and deer. Mini-tunnels (caterpillars) also give a jump start in spring. The French use these for strawberries, said Gros, and they are useful for kale and spinach.

His main outdoor crops in early spring and late fall are spinach, kale, arugula, baby greens mix, bok choy and turnip. For spring sales, he direct seeds these from February 1 to March 15. Extreme weather in early March, such as tornados, can be difficult, noted Gros.

His caterpillar tunnel is 8 feet tall, 17 feet wide and 100 feet long and cost about $1,500 to $2,000, or about $1 per square foot. It has no internal support or cross beams, but its low profile reduces its susceptibility to winds. The ends and the east side are always open for ventilation. (Winter winds come from the west in his area.) This tunnel offers freeze protection down to about 5 F.

His next-level structure is a 30-foot-wide, 15-foot-high, 100-foot-long tunnel costing about $3 per square foot and available from Morgan County Seeds in Missouri. This provides protection against killing freezes down to 0 F. Unfortunately a 100 mph wind destroyed part of this tunnel.

In 2016, Gros had a custom, Amish-built tunnel erected. “The whole concept of shape is transformed” in this 10-foot-high, 24-foot-wide, 150-foot-long house. It captures a lot of heat but is shorter and stouter than his previous high tunnel; he hopes it will be more resistant to high winds. This structure also cost $3 per square foot and provides protection against killing freezes down to 0 F.

Planning depends on temperature, crop hardiness, marketability, growing ability, soil factors, plant density and plant positioning. Tunnels shift the growing season by a full month and eliminate the risk of a total crop loss from a deep freeze. Top crops for withstanding cold nights are collards, spinach, mache and turnip. Gros said to position the hardiest crops in the outside beds of the tunnel. His PowerPoint lists the best winter crops for his area.

Regarding marketability in his area, the winter stars are carrots, spinach, kale, lettuce and baby greens mix, with a “supporting cast” of arugula, cilantro, turnip, scallions and chard, and the “extras”: collards and mustard. “In winter people are so much more excited to see anything at market,” said Gros. “You’ll be a hero in your community if you have these in January and February: cabbage, baby greens, lettuce, spinach, cilantro, kale and carrots.

Regarding ease of growing, Gros listed his “problem-crops” for winter: spinach, carrots and cauliflower, due to poor germination, questionable hardiness, sensitivity to insects, diseases and weeds, and more. His easily grown and marketed “dream crops” are lettuce, cilantro, arugula, bok choi and kale. “Some varieties will stand out in term of hardiness or overall adaption” to an area, he added.

Gros said winter growing has not generated any particular soil fertility requirements that differ from his overall farm strategy. “Tunnel fertility requirements are met the same way as outside.”

He is still experimenting with crop density, which depends on soil fertility and light access. He is trying up to five rows of lettuce and seven rows of cilantro on a 4-foot bed.

Lettuce leads in terms of profitability in winter. One 100-foot-long bed in his tunnel produced $1,000 in sales in November.

Rotation inside tunnels is challenging due to the limited space and number of crops grown. Gros thinks that rotation is needed only in problem soils, while the microbiology in healthy soils will meet specific needs for specific plants. “Plants produce exudates, specific chemistry to help nourish themselves with needed nutrients,” said Gros. Since organic certification requires rotation, however, he does try to alternate plant families in his tunnels.

Two “waves” characterize winter growing for Gros. From September to January, he progressively replaces such summer plants as tomatoes and peppers so that new crops gain maximum growth before the weather cools. Most beds are seeded or planted by December 1, and some are in full harvest during this time. Plants grow slowest from December to January; production then is from mature plants.

In the second wave, from January to March, he progressively replaces harvested beds from the first wave by seeding the hardiest crops (spinach, radish, kale …). Transplanting is not recommended in the coldest January-to-February period.

Gros noted that a 250-square-foot bed of kale in one low tunnel generated $1,156, or $1.16 per square foot, during the first wave. All first-wave crops combined produced $11,000, with another $7,000 generated in the second wave – totaling 22 percent of his $80,000 annual sales.

He treats winter pests – white flies, aphids and sometimes spider mites – with insecticidal soap and/or oil. He controls his main weed, chickweed, by hoeing or mulching, depending on the crop in which it is growing.

Gros has written three short books about his techniques, available for $10 each or three for $25 from Gros ([email protected]).

– J E

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