Frost Protection

Frost Protection

Recent hot weather has perhaps lulled us into forgetting that fall is upon us. But, soon, that first frost shall arrive. For gardeners who are prepared, an early frost does not need to halt the gardening season.

The first frost or two is often followed by several weeks of good garden-growing weather. Gardeners can take advantage of these extra gardening weeks by protecting their plants through early light frosts.

Plants vary in their susceptibility to cold temperatures. Tender crops, such as tomatoes, peppers, melons and okra, cannot withstand frost, unless protected by some insulation. Cool-season crops, such as cabbage, broccoli, Brussels sprouts and kohlrabi, will tolerate frost or even a light freeze. Other crops, such as beets, carrots, lettuce and potatoes, will stand a light frost.

Mulching is a good way to protect very small gardens. Use several layers of newspaper, straw or chopped cornstalks. For those with large gardens, it may be more practical to protect only a few plants of each crop. Blankets, tarps, floating row covers or other large materials can be placed over rows of vegetables to supply insulation. Cloches, paper tents, hot caps and plastic walls of water are the more expensive approaches to frost protection but are very effective. In cases of light frost, sometimes only the upper and outer foliage are damaged, and the plants can still continue production.

If plant covering is not feasible, pick as much produce as possible, if frost is predicted. Some crops can be further ripened indoors, if they are not fully mature. Most green tomatoes can be ripened to full red indoors. Light is not necessary to ripen tomatoes. In fact, direct sun may promote decay of the fruit due to excessive heating. Ripening is mostly affected by temperature — the warmer the temperature, the faster the ripening. To store tomatoes for later use, wrap the fruit individually in newspaper and store at 55 F. The fruits will gradually ripen in several weeks.

The following chart lists the most commonly grown vegetables and indicates their tolerance to frost.

Cold Temperature Tolerance of Vegetables

Tender (damaged by light frost)
Beans
Cucumber
Eggplants
Muskmelon
New Zealand Spinach
Okra
Pepper
Pumpkin
Squash
Sweet Corn
Sweet Potato
Tomato
Watermelon
Semi-Hardy (tolerate light frost)
Beets
Carrot
Cauliflower
Celery
Chard
Chinese Cabbage
Endive
Lettuce
Parsnip
Potato
Salsify
Hardy (tolerate hard frost)
Broccoli
Brussels sprouts
Cabbage
Collards
Kale
Kohlrabi
Mustard Greens
Onion
Parsley
Peas
Radish
Spinach
Turnip