It was his “disinclination to give over his markets to the Californians every fall” that first piqued organic grower Eliot Coleman’s interest in four-season vegetable production at his Harbourside, Maine farm. While traditionally growing vegetables in the winter has meant using heated greenhouses, Coleman, a true innovator, sought a different approach. He wanted to see how much he could produce without supplemental heat.
Simplicity, low external inputs, and high-quality outputs were the guiding criteria for his year-round gardening system. “Our goal was to find the lowest tech and most economical way to extend fresh-vegetable harvest through the winter months,” he says. Coleman, who has been growing vegetables year-round on a commercial scale since 1995, has developed a fine-tuned growing system through his attention to detail.
Last year he produced $120,000 worth of vegetables from 1.5 acres, with only a quarter of an acre under cover, using very little supplemental heat.
Farming on the “back side of the calendar,” as he calls it, has many advantages. It means he can hold his markets, keep his crew employed, and it provides a more balanced year-round income, he says.
Growing vegetables year-round at Coleman’s Maine farm is no small feat. Located two-thirds of the way up the Maine coast on the 44th parallel, temperatures can dip as low as -29 degrees C. Using standard, plastic-covered, gothic style hoop houses allows Coleman to mimic growing conditions 500 miles south of his farm. Adding a second layer of protection, a floating row cover 30 cm above the soil, simulates growing conditions a thousand miles south of his farm, he says. Coleman calls his unheated greenhouses “cold houses,” as opposed to “hot houses.”
“Using the double layer of protection lengthens the growing season on both ends, basically for free, no heat required,” he explains. The only cost is the cost of the greenhouse and the row cover material.
Another key to the system is growing vegetables that do well in the cold instead of heat-loving plants such as tomatoes. These vegetables include spinach, Mesclun (a mix of baby salad greens), carrots, mâche, watercress, and potatoes. Many cold-tolerant vegetables can easily survive temperatures down to -12 degrees C or lower as long as they are not exposed to the additional stresses of outdoor conditions, he explains. The double coverage also increases the relative humidity in the protected area, which offers additional protection against freezing damage. Any type of lightweight floating row cover that allows light, air and moisture to pass through is suitable as the inner layer of material in the cold houses, he says.
Coleman maximizes the use of his greenhouses by moving them to where they’re needed. For example, he starts spinach in the greenhouse and once it’s safe from frost, about the third week in March, he can move the greenhouse to another location and use it to start another crop like carrots. By the end of April, the carrots no longer need protection and then he can start another crop like zucchini. This allows him to double the use of his capital investment in the greenhouses, he says. “We became involved with greenhouses because of our interest in growing winter crops and then wondered how to best use them for the rest of the year,” he says.
Planting at the right time for your conditions and environment is also crucial, he says. “For example, the trick with winter-harvest crops is to get the seeds in the ground in September, not November, so the crop has a chance to grow and put out new leaves,” he explains. “I think of August-September as the second spring.” Successive seedings also ensure a continual harvest.
Coleman didn’t invent the moveable greenhouse concept. This was actually a technique used by vegetable growers in the 1890s, he says, before chemicals were available to sterilize the soil in the greenhouse. Rather than completely digging out and replacing the soil in a greenhouse, an extremely labour intensive job, the growers would move the greenhouse to a new location. This is just one of many techniques Coleman learned about through his hobby of reading old books. There’s a wealth of knowledge in books from before the 1940s, in the pre-chemical days, he says. “The basic ideas haven’t changed…there’s just some new technologies.”
Since early harvests can bring considerably higher prices for produce, Coleman tries to have tomatoes ready when his farm stand opens in early June. He aims to have peppers for sale two to three weeks after that. “Hoop houses can give a four to twelve-week jump on maturity without heat,” he says.
Coleman’s four-season growing system is not static, he emphasizes. “We are continually evolving.” His research is ongoing to determine precise planting dates and greenhouse space allocation for each crop to have as wide a variety of vegetables available continuously and he’s also looking for varieties that will germinate in cold soil or that are less prone to bolting in the summer heat. Coleman prefers to sell a wide variety of fresh produce into local markets (within 25 miles) rather than producing a lot of one type of vegetable and shipping it great distances.
“There are many possibilities still to come, we are only scratching the surface of what the winter harvest is capable of supplying,” says Coleman who thinks that his nontraditional winter vegetable production system has potential for growers in any part of the world where cold weather currently restricts production.
Winter harvest of a wide variety of crops would be a logical step for farms who market their crops through Community Supported Agriculture. “Instead of increasing the number of subscribers you can increase the number of months you supply them,” he points out.
Coleman farms organically using what he calls deep organic techniques. “Deep-organic farmers, in addition to rejecting chemicals, look for better ways to farm. Inspired by the elegance of Nature’s systems, they try to mimic the patterns of the natural world’s soil-plant economy,” he says in his book, The Winter Harvest Handbook. “We don’t have to control nature, we can work with it.”
On the other hand, shallow organic farmers look for quick-fix inputs, he says. They mimic chemical agriculture using bagged or bottled organic fertilizers and arming themselves with the latest organic weapons to treat insect and disease problems.
It’s the organisms in the soil that make the whole system go, says Coleman who was inspired many years ago when he first learned there are a million live organisms in a teaspoon of fertile soil. Compost is the world’s best fertilizer and can be made from any waste such as spoiled hay, cabbage leaves, manure or carrot tops, he points out.
Coleman offers the following advice for those who want to try their hand at winter vegetable production. First you need to determine if there is a market. If so, start small untill you can wrap your head around it, he says. For example, if you have a greenhouse with some benches for growing bedding plants, he suggests trying to grow watercress or baby leaf lettuce in potting soil in flats. His final piece of advice: “Don’t quit your day job.”
Coleman’s book, The Winter Harvest Handbook (2009), gives a detailed explanation of the evolution of his four-season growing system. He wrote the book to pay back all the nice people who shared what they knew with him, he says. “I want to pass this information on to the next generation,” he adds. “Organic farming will work when the coal and oil run out. That’s how we’ll be feeding everyone’s grandchildren, might as well get started now…before we’re desperate.”
It’s easy to see why Coleman, a former mountaineer and adventurer, chose agriculture as a career even though he didn’t grow up on a farm. “Agriculture is like a mountain that you can never get to the top of…it’s a learning curve that goes on and on and on,” he says. “And the best part of mountain climbing was always the figuring out how to get to the top, not the actual getting there.” It’s this sense of wonder and curiosity that will continue to drive the 71 year-old Coleman in his pursuit of an ever-better growing system.
Coleman’s farm stand at his Four Season Farm is open from June to September. “It’s hard to tell the customers from all those who are looking around,” he says with a laugh.
More information can be found on Eliot Coleman’s website at www.fourseasonfarm.com. In addition to The Winter Harvest Handbook, he has written two other books: The New Organic Grower (1995) and the Four Season Harvest (1992). He is married to horticulturalist and author Barbara Damrosch.