Yes, we can... grow vegetables during the winter
This article was first printed in the March/April 2009 issue of the Organic Broadcaster, published by the Midwest Organic and Sustainable Education Service.
On a very cold winter day in January (minus 35F), over 160 people convened in St. Cloud, Minnesota to hear Eliot Coleman of Maine explain his continually improving methods for growing a mix of greens and vegetables through the fall, winter and into spring. Eliot uses a system of minimally and unheated hoophouses, many of them setup to move 2-4 times in a 12-24 month period in a straight line down a field. This allows him to both grow and incorporate robust green manures as well as start his longer seasoned crops in the outdoors, before moving the greenhouse over them for the winter. Eliot enjoys the challenges that come with continually seeking out more efficient farming methods and tools that do not rely on large equipment or capital outlay. Winter growing is not reserved only for commercial growers, home gardeners on small scale can adapt these methods with minimal outlay and maximum eating pleasure!
Over 20 years ago, Eliot made his first visits to Europe to learn from the market farms there serving customers with high quality vegetables year-round. Still finding inspiration from these early and subsequent trips, the crops he grows, the fertility program he uses and the structures in place on his Four Season Farm continue to evolve each year. A basic tenant of season extension is that for each layer of protection you add, you move the growing environment under that protection 1.5 zones south. Eliot gave the example…from zone 4 in Maine (WI too) to Zone 5.5 in New Jersey with one layer of protection to zone 7 Georgia, with two layers. Eliot first saw this type of protection done very simply, but on a large scale, using glass covered cold frames with woven straw mats used on top of the glass for the second layer. These days, you gain these layers mostly with various layers of plastic and spun polyester row cover. Cold frames could also be built inside a hoophouse.
Eliot doesn’t only rely only on greens for his four season harvest, he plants carrots on August 1st into coldframes and covers these with loose straw. He can harvest these all winter long, labeling these cold sweetened carrots as “candy” carrots (Napoli, minicor, nelson varieties) to help his customers recognize the special taste of these locally grown treats. Eliot explained various interplanting systems done in Europe, with radishes and carrots interplanted with lettuce. When the radishes are harvested, cauliflower is planted about 2 weeks before the carrots are harvested. The lettuce crop is exhausted by the time the cauliflower is shading it. This uses the high value real estate in the greenhouse most efficiently, but does take good timing and labor for transplanting into existing plantings.
In the north we live with short days and it is important to plant winter harvested crops no later than early to mid September, so they have a chance to mature before the natural light is 9 hours or less. Many varieties of greens, including spinach and specific varieties of salad mix lettuces, are very well suited to “cut and come again” type culture. If they are kept from long periods of freezing they will keep growing (although slowly) even through the dark days of December. Mid-January to February they grow quite rapidly responding to the longer days and the increased warmth from the sun. By mid to late March some may even be starting to bolt, and can be replaced by early carrots and beets. Cucumbers and tomatoes are transplanted in early April for an early season harvest. Lettuce can be planted midsummer under the cucumbers for an early fall harvest. All these various scenarios are not used in one area. Eliot leaves time each year for soil building, either splitting up the areas in the greenhouse for this important task, or moving the greenhouse over the field. For instance he moves the hoophouse that he uses through the summer down the field in the fall, and plants a winter cover where the summer vegetables had been. The greenhouse is now covering his fall leek crop, which had been growing without cover all summer. He can then harvest the leeks all winter.
Eliot plants his greens in 30-36 inch beds, 10-12 rows to a bed, with approximately 10-12 inches of walking row between these beds. He likes "pro 17" spun row cover put over galvanized metal hoops for his secondary cover inside the hoophouse. Keeping the row cover off the plants preserves quality. He found that moving the secondary cover on and off during the day made no difference in growth, so now he only removes the spun polyester when harvesting. The row cover also retains some moisture, making water chores less frequent.
Eliot had many tips for commercial growers, reminding people to continually plan and experiment with crops and marketing to make the farm economically viable. He experimented with many types of crops in the hoophouses including broccoli (not so good) and kale (new leaves don’t grow as readily as spinach and lettuce). Claytonia is a nice green, and adds weight when making a salad mix, (remember, the crop is sold by the pound!) Bulls blood beet produces nice greens, buckshorn plantain adds crunch to the salad mix, red oakleaf and rouge de vetter red lettuces are especially winter hardy, and a variety of asian greens add spice and texture, such as mizuna and Tokyo open hearted Chinese cabbage. Eliot sells swiss chard leaves when they are the size of your hand, no larger, as a baby green, and gets more dollars per pound for this more succulent version. Having a variety of offerings other than only lettuces also helps his sales, including curled parsley, watercress (grown in 2.5 inches of potting soil in trays), radishes (tinto variety is one of his favorites at this time), baby turnips (golf ball sized, sell with tops), carrots with tops (clearly differentiates a fresh local crop from stored local crop), and baby bok choy. Eliot strives to have the crop being harvested make $1.50 per square foot for at least two months.
Eliot has a concrete slab at one end of a hoophouse. He moves the hoophouse back and forth, so this area rotates at either end. This area has water available and also has been fitted with heating tubes in the concrete for a heated floor. He uses this as a giant heating pad in the spring for germinating flats of transplants, and presprouting potatoes before planting (keep them misted so they don’t dry out). This hoophouse is considered minimally heated. In this greenhouse he plants peas in February for harvest in early April (doesn’t that sound good). This concrete area has multiple uses with various washing and packing operations used as needed. Eliot likes to grow and wash each different green separately, so when the greens are floating, he can easily pick out the lower quality leaves. This is not as easy when the greens are mixed. He built a wooden green turner, which receives the washed and spun greens and mixes them before bagging.
Eliot is an experimenter, and at this workshop he shared the various configurations he has used over time to move his greenhouses. His latest version consists of a pipe and wheels that moves along a moveable track. His book the Winter Harvest Manual, which has been updated and greatly expanded, should be released later this spring, and will have the various systems explained in detail. One item of great importance is to make sure that you plan for good anchoring of your moveable hoophouse. You only want it to move where and when you want it to move, not in a wind storm when you have it full of ready-to-harvest high value crops. A variety of tools have been developed by Eliot Coleman for use both in hoophouses and in the field and are available through Johnny’s Seed, at the Organic Farming Conference (February 27 and 28 in La Crosse) and through other outlets. These tools make high density plantings easier and include a tillage broadfork, a small rototiller that uses a cordless rechargeable battery type drill as its power source (no exhaust fumes with this rototiller), and various seeders with rollers which help with soil-to-seed contact and better germination for small seeded crops.
If this article has whetted your appetite for extended season production, both the Organic University and the Organic Farming Conference in 2009 will have excellent presentations by Bill Warner/Judy Hageman of Snug Haven Farm (spinach through the winter as well as other crops) and John Biernbaum, horticulture professor at Michigan State (wide variety of crops and experience). If you miss the conference, you can go to the MOSES website and purchase recordings of the conference sessions. On a personal note, I have a solar greenhouse on my farm in SW Wisconsin, and I can testify that having lettuce, spinach, kale, celery and fresh herbs all winter without any supplemental heat is possible and worth the trouble!
Harriet Behar is the MOSES Outreach Specialist. She was an organic inspector and inspector trainer for many years and has an organic bedding plant and vegetable operation with her husband in Southwest WI.Return to TOP