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How to grow vegetables all winter long
Defy winter and grow your vegetables year-round, even after the first frost.
For most gardeners, winter means staring out the window, making plans for spring and pining for better weather. “This is the season of lists and callow hopefulness,” Katharine White wrote in her 1979 seminal work, Onward and Upward in the Garden. “Hundreds of thousands of bewitched readers are poring over their catalogues, making lists for their seed and plant orders, and dreaming their dreams.”
Although the growing season in Atlantic Canada is short, with about 130 frost-free days, an increasing number of gardeners are using inexpensive and innovative methods to extend the growing and harvesting season through the coldest months of the year.
“I pulled carrots from the ground in late November and early December last year,” says Niki Jabbour, a Halifax-based garden writer whose first book, The Year-Round Vegetable Gardener, comes out in mid-December.
Off-season gardening is “ridiculously easy,” Jabbour says. “There are so many different crops you can grow. I just think people don’t know they can do it because they think it’s too cold. But it’s not the cold—it’s the amount of light we receive.”
Plants will stop growing when there are fewer than 10 hours of daylight available, Jabbour explains. She says the key to success is knowing what to plant at what time of year and selecting cool-season vegetables like lettuce for fall planting.
“If you plant lettuce in late August when it’s hot, it’s not going to germinate for you,” she says. “So you have to plant at the right time, grow at the right time and eat at the right time.” You also need some form of cover to protect against frost and wind.”
Many gardeners use fabric row covers made of spun polyester to extend the growing season by a month in either direction. You can also use bell-shaped cloches to cover and protect individual plants. These are available at garden centres or you can make your own at home from old milk jugs.
Cold frames, or bottomless boxes with clear tops, are popular season extenders. You can build these from wood, brick or straw bales, covered with old windows or greenhouse plastic. Another option is a hoop house or mini-tunnel, consisting of plastic or metal conduit bent around a raised bed to create a hoop. The whole structure is covered with plastic sheeting, allowing light to reach the plants but protecting them from frost, snow and wind.
A self-described lazy gardener, Jabbour appreciates that cold-season gardening involves less maintenance than warm-season gardening. “In the middle of winter, there are no bugs, there are no slugs,” she says. “And because the plants are covered in a cold frame or mini-hoop tunnel, there are no deer. All I do is harvest in the winter.”
Certain vegetables—like carrots, parsnips, leeks and kale—are even sweeter in winter because their starches turn to sugar as a natural form of anti-freeze. “It makes them taste better,” says Jabbour. “I don’t even pick carrots until we get a couple of frosts.”
By pushing the gardening season later into the year, she was able to discover vegetables she had never heard of before, such as mâche (a small, nutty green common in Europe), claytonia (miner’s lettuce), tatsoi and mizuna (the latter two, Japanese greens). Jabbour says being open to new tastes, textures and flavours, and trying something new each year, have been highlights of year-round gardening.
A few hours away in Darlington, Prince Edward Island, Amy Smith and Verena Varga operate Heartbeet Organics. They tried cold-season gardening for the first time last year after buying a house that came with two large greenhouses.
“Last winter was intense in P.E.I.,” Varga recalls. “Sometimes the snow went halfway up the outside of the greenhouse.” Despite the weather, Smith and Varga managed to be among the few purveyors offering fresh spinach and salad greens in mid-winter at the Charlottetown Farmers’ Market.
Although their greenhouses were equipped with propane heaters, they wanted to try growing without heat. Smith planned on testing some of the techniques she had read about in books, especially those by Maine-based gardener and writer, Eliot Coleman.
“We had no idea what would happen,” she says. “We were really experimenting.” The pair had good success with mustard greens, spinach and bok choy, but had trouble growing mâche.
“We heard it was a great late fall or winter crop,” Smith says. “But it was a major disappointment. It germinated and then went dormant. We expected it to be the best crop but it was the worst.”
Trial and error is part of the game, Smith says. She kept detailed records of the crops they planted and carefully tracked the amount of daylight throughout the fall and winter to mark when they had crossed the 10-hour threshold.
“The biggest challenge was getting the snow off the greenhouses,” says Varga. “But being inside was almost therapeutic because it was so warm and humid in the middle of winter.”
One big thrill came on New Year’s Eve, when the couple had family visiting. “We were making a New Year’s feast and we went out to the greenhouse and cut some baby bok choy and made a salad out of it,” Varga says. “The joy we got from being able to run out and snip some greens and have a salad in winter was just awesome.”
What to plant (Courtesy Alison Lynes, Halifax Seed)
Plants that can overwinter for early spring harvest:
- alliacea (garlic, leeks, onions)
- herbs (thyme, oregano, sage, chives)
- root vegetables (turnips, carrots, parsnips)
- greens (spinach, kale)
Plants for late-fall/winter harvest:
- brassicas (broccoli, rapini, Brussels sprouts, cabbages, kohl rabi)
- root vegetables (turnips, rutabaga, carrots, beets, radishes, parsnips, Jerusalem artichokes)
- greens (kale, bok choy, collards, swiss chard, spinach, arugula)
- Pick varieties that grow to maturity in short time periods.
- Water less in the late fall to prevent freeze/thaw cycles from splitting vegetables.
- Plant greens, lettuces and herbs every few weeks to ensure continuous harvest throughout the season, including late into fall.