JN Gardens

Winter Vegetable Gardening

You don't need to live in the balmy zones or own a greenhouse to keep on growing through the winter. All you need to do is choose the right crops and varieties, time the planting right and employ a few smart techniques. All of which we have for you right here.

What to Plant
All of the brassicas—broccoli, cauliflower, cabbage, kale, brussels sprouts, collards, turnips, bok choy—are great candidates for overwintering. So are root crops, such as carrots, radishes, parsnips, beets, onions, potatoes and leeks. Many greens, including lettuce, spinach, mustard, mache (corn salad) and Swiss chard, like it cold, too. We name a hardy variety or two of each here—the descriptions in your favorite seed catalogs will help you find more.

Timing
Plants that are close to 90 percent grown will endure cold temperatures well. To know when to sow seed or transplant crops you want to grow over the winter, you need to do a little figuring. Start with the variety's days to maturity (which is usually on the seed packet), then add 10 days to allow for the shorter growing days of fall. Now count back that number of days from your average first frost date (if you don't know that date, call your county extension office)—the date that results from counting back is when to direct-seed or transplant.

Now cover your bets against the unpredictable fall weather by staggering your plantings over a two-week period and grow several different varieties.

Techniques
Row covers can protect plants from the first frosts of fall through the winter, according to Otho Wells, Ph.D., vegetable specialist at the University of New Hampshire. Dr. Wells conducted tests to see just how well row covers would protect fall-sown lettuce and spinach. "We seeded as late as possible with the plants still having time to germinate," which was on October 1, he reported. "As soon as we seeded, we covered the bed with row cover, secured along the edges with soil. When we took the cover off on May 21 the following spring, the plants were large enough to harvest.

"The plants had been able to grow about 1 to 2 inches across before frost hit and stayed that size all winter," Dr. Wells explained. Control plants that had been left uncovered did not survive.

You can also use old sheets, blankets and afghans to cover young plants. Do not use plastic mulch as nighttime protection the plastic conducts cold to any plant it touches.

Row covers and sheets aren't the only option for winter protection. Richard DeWilde, a gardener in Wisconsin, sows spinach and oats together in the fall, and when the oats are winter-killed, they fall over and cover the spinach. A mixture of ryegrass and clover forms an even denser mat of protection.

No matter what technique you choose, one of the keys to overwintering success is to gradually acclimate the plants to the cold. That's why they'll need more protection from an early cold snap than a later one.

Bear in mind that clear, dry and windy conditions at night are harder on plants than cloudy, damp nights, because moisture in the air moderates the temperature. Use row covers, blankets or sheets on clear nights. Just be sure to remove those coverings when the sun comes up in the morning, so you don't cook your plants before you're ready to harvest them.