Hardy Harvest: Bountiful fall crops are ready just in time for Thanksgiving

It's always a delight to harvest vegetables right out of the garden for Thanksgiving. We are fortunate that several fall crops will sail into November and December -- and some can even hold their own to next spring.

Last year, I enjoyed scallions and spinach in the spring. They had held through the winter and started growing once the weather warmed. In this exceptional fall season, protected gardens are still putting out a few tomatoes, a delightful treat this time of year.

In the South, such traditional cold-season crops as collards and kale are standard practice. Not only are they enjoyed during Thanksgiving, but they are an important part of the New Year's celebration.

Several root crops can readily take temperatures below freezing, particularly parsnips and rutabagas. Carrots are fairly hardy, and it is a joy to pull them -- bright orange from the cold earth. Beets are pretty tough, too, and can be found both golden and red.

Leeks can be fun to grow. The stalk is the edible part of this onion-family plant. The more stalk grown under ground, the larger the edible portion. By hilling and trenching, the stalk is extended. Winter is the time to carefully dig and harvest the stalk to make leek and potato soup, just the thing on a cold day.

Mustard cabbage, kale, broccoli, cauliflower and Brussels sprouts are other popular winter subjects for the garden.

Many vegetables are border-line cold hardy -- they can take the cold but not a whole lot of it. Few vegetables can rival fresh peas from the garden, but it can be tough to get the timing right. Plant too early in the autumn and the lingering heat can slow things down. Plant too late and an early frost can nip the flowers. They will only take it down to 30 degrees. The same is true of most varieties of lettuce. Too much heat and they will run to seed causing the leaves to be bitter, and temperatures in the 20s will turn them to mush.

With touchy crops such as these you can push the boundaries a little with a spun-bound, agricultural fabric, also called a row cover. This simple fabric can be draped onto crops and will increase temperatures by about four degrees. It may not sound like much, but the wind is excluded and moisture is retained.

A good mulch will also help to regulate temperatures and keep a little warmth in. On very cold nights, a straw or leaf mulch can be thrown right over the plants to protect them.

Another method is to construct a bottomless cold frame in the garden. These are wedge-shaped structures. The front is a glass or plastic window that can be hinged up and supported in warm weather and closed for cold nights. You can take the cold frame a few steps further by adding insulation. Michael Rahman, whose square-foot gardening project I discussed in an earlier column, has adapted his beds to accept a cold-frame cover of corrugated polycarbonate. It is further insulated with rigid foam to retain some of the day's solar heat. He also added a vent, designed for ventilating house foundations. It opens automatically when the sun heats things up inside the frame.

The ultimate step in season extension is the high tunnel, what most of us would think of as an unheated hoop greenhouse. I visited the N.C. A&T State University farm during its field day in November. Rickie Holness demonstrated the growing techniques he uses to coax vegetables out of his high tunnel.

Holness is an extension associate coordinator for applied research. He had tomatoes, lettuce, scallions, herbs, spinach, peppers and cucumbers growing organically in this system.

Weather determines the length of the harvest, but Holness said that he will continue to harvest warm-season crops until anywhere from mid-November to mid-December. Holness had tomatoes planted in black plastic bags that he started in August. Lettuce was mulched with white plastic to keep the plants cool, the roots warm and to keep soil from splashing on the leaves. The high tunnel allows for premium crops during the off season, and they will command an equally premium price.

"We have gone down to 36 inside the tunnel this year," Holness said. "Warm-season crops will not take a sustained period below 32 degrees."

How long this year's mild weather will provide the illusion that we do not need such innovations as high tunnels is yet to be seen. But for now, I enjoyed cherry tomatoes on my Thanksgiving salad -- straight from the garden.

If you have a gardening question or story idea, write to David Bare in care of Features, Winston-Salem Journal, P.O. Box 3159, Winston-Salem, NC 27101-3159, or send e-mail to his attention to gardening@wsjournal.com.