Harvesting in the winter is possible with a little preparation
Most Canadian gardeners enjoy bounties of fresh vegetables throughout the summer and fall, only to abandon their horticultural pursuits as winter blows in. But some see the cold months as another opportunity for harvest and continue to enjoy fresh produce from their gardens.
In central Nova Scotia, organic farmer Norbert Kungl harvests winter greens such as kale and spinach through the winter in an unheated greenhouse, despite blizzards and temperatures that drop as low as –20 C. And on Vancouver Island, organic farmer Carolyn Herriot feeds her family winter greens, turnips, beets, and in the early spring, cauliflower, cabbage and broccoli from her garden.
"In the Pacific northwest coastal region, we enjoy a micro climate, so winter gardening is really not a problem at all," says Herriot, author of A Year on the Garden Path: A 52-Week Organic Gardening Guide.
With a little ingenuity, even those in some of the coldest climates in Canada can enjoy a winter harvest. "I have always thought these ideas [winter harvesting] would work as far north as the 60th parallel," says Eliot Coleman, author of Four Season Harvest: Organic Vegetables from your Home Garden all Year Long.
Carol McIntyre, a grower on Vancouver Island who conducts workshops on winter vegetables, says that Coleman might be a bit ambitious in thinking harvesting in the coldest months can be conducted that far north, but she has had attendees at her workshops harvest vegetables as far north as the 50th parallel. "We're seeing new things all the time, though," she says.
One option for those in the coldest parts of the country is growing small pots of sprouts inside the home.
"I sprout seed mixes inside. Broccoli, alfalfa, mustard, cress, and wheatgrass, all these are nutrient-packed greens that can be grown on a window sill," says Herriot.
The recipe for winter-gardening success, however, is to be realistic about what you're planning to grow. Although there are some people who try to cultivate things like tomatoes and peppers indoors with artificial light, Herriot advises against this, saying it is difficult, the yields are low and the produce is generally flavourless.
Coleman, who has an organic farm in Harborside, Maine, sells produce from his garden at the local market year round. And this is done in a climate where temperatures can dip as low as -25 C in the winter. According to Eliot, producing food in cold climates where sub-zero temperatures are the norm requires one tool — the cold frame.
Place cold frames in sunny spots
Cold frames are wooden structures with clear glass or plastic tops, which are used to cover plants to protect them from the elements. These can easily be constructed out of old window frames and pieces of wood. The cold frame acts like a miniature greenhouse, trapping the warmth from the winter sun. The inside of a cold frame can be up to 11 degrees Celsius warmer than the outdoor air, according to Coleman.
To keep the inside of these structures even warmer, Kungl recommends placing them against the sunniest wall of your house, so it will get the warmth from the sun and the ambient heat from the home. Often this isn't necessary, however, as on the sunniest of days it can become too warm in a cold frame, and then it's necessary to prop open the top and allow cool air to circulate.
In the darkest, coldest months of January and February, the plants in the winter garden slow their growth to a near standstill because the day length is so short. Even though plants such as winter greens may not grow much, the leaves can still be harvested, providing a source of fresh food. McIntyre calls this "using nature as if it were a fridge."
To harvest in the winter, though, many plants must reach maturity before the cold weather settles in. Herriot selects seeds for her winter garden at the same time she orders her seeds for the summer garden.
"For me, it's not an afterthought," she says. "When I think about food growing, I'm actually thinking about the entire year, not just the summer garden. A lot of people don't factor in the winter garden and they scramble around trying to get seeds at the last minute."
Herriot plants most seeds for her winter garden in mid-July.
"My formula is to have everything in the ground and established by mid-September," she says.
Herriot harvests cold hardy crops like parsnips, beets, turnips, leeks and carrots, through the fall and into December. Winter greens like Red Russian kale, Dutch green curled kale, perpetual spinach, Swiss chard, arugula and broadleaf cress provide salads for Herriot's family right through until April. With the mild coastal winters, Herriot does not need to protect her greens with cold frames, but uses mulches. Even without cold frames, winter greens have proven hardy in some frigid conditions.
McIntyre says that the last two winters have pushed the limits of her winter garden. "[There has been] two feet of snow, -15 degree [temperatures] and harsh winds. As the snow cleared off my bed this week, I saw that some of the greens have been hard hit, but are alive, and judging from last year after a similar snowfall, will come back."
Grow what you like to eat
For the beginner winter grower, both Herriot and McIntyre recommend experimentation.
"Be willing to try, observe, and experiment; and trust your experience and intuition," says McIntyre.
A seed catalogue will give you guidance on what vegetables are feasible for growing in your region, and how hardy they are to cold temperatures.
Herriot adds that people should grow what they like to eat.
"Just put in those things that you enjoy eating to get you excited about it," she says. "Then you'll have the motivation to harvest."
For people acclimated to buying tomatoes and strawberries in grocery stores during the winter months, it can be a struggle to get excited about eating less 'exotic' foods, but Herriot says it's not only better for the environment, it's healthier.
"Nutritionally, we are adapted to eating what food is given to us locally, but recently we've become disconnected from that," says Herriot.
"In northern climates, what the body craves in winter is food high in carbohydrates and some vitamin-packed greens," she adds.
McIntyre points out that there have been studies that show foods grown in tropical climates are not necessarily the healthiest winter food choice for people in the northern hemisphere. "People are more aware of the health and environmental benefits of eating locally grown produce," she says, adding that attendance at her workshops has been steadily increasing.
"I'm 60 years old, and when I was a kid, we just did not have the varieties of produce available in winter .… We had turnips," she says with a laugh.