September
2004
By
B. Rosie Lerner
Extension Consumer Horticulturist
Purdue University
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Gardeners Should Prepare to Avoid Frost
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
9-16-04
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