Give frost the cold shoulder by protecting your plants

NEW MARKET, Va. -- About this time of year, many gardeners become gamblers, trying to coax a few more weeks of growth from their plants before the first killing frost arrives.

A dicey game, that. And it's a situation where the odds are not with the house.

Frost is no respecter of blooms, late ripening vegetables or plant pedigrees. A clingy chill can blacken them all. Surviving plants may be seriously weakened, making them more susceptible to insects or disease.

But there are a number of things you can do to stretch your garden season. A good way to start is by gathering some information.

"You need to know the average date of your first frost and something about the hardiness of your favorite plants," says Larry Caplan, a Purdue University Cooperative Extension agent working out of Vanderburgh County in Evansville, Ind.

"You also have to know something about your general (USDA) hardiness zone: Not only the first frost but the average cold temperatures through winter," Caplan says.

Knowing when to expect the first frost gives you some margin for error. But it's generally best to winterize now, while working conditions are still comfortable outdoors, rather than try wrapping things up on a chilly November weekend. Call your local weather bureau for the average first and last frost dates in your area or look them up on the Internet.

Knowing how cold it might get tells you how thoroughly your perennials, shrubs or trees should be protected to help them survive winter.

Use location to your advantage. Low-lying areas are likely to be "frost pockets," as much as 15 degrees cooler than ground near the foundation of your house. If you want to try wintering over some chrysanthemums, place them there.

Plant tender species on high ground or on slopes, where cold air will move on by rather than linger. Even a slight breeze helps prevent frost from settling in on a cold, clear autumn night. Plug in an electric fan if you have a corner of your vegetable garden you're still trying to protect.

If you do nothing else, you usually can buy time for your plants or help them through winter by watering, composting, covering or moving.

Soak them heavily, shrubs and trees included, at least until the first frost. "Irrigating will help keep plants out of drought stress," Caplan says. "They'll be able to survive cold snaps better."

Sprinklers often are used to protect vulnerable vegetable gardens and orchards. Saturating soils early in the day may help protect plants from frost damage since the water will warm and release its heat slowly during the night, Caplan says. Sprinkling the plants with water on frosty nights also can help prevent injury.

Add a couple inches of compost, but wait until after a frost.

"If you mulch heavily the last warm weekend in October, it warms plants," Caplan says. "It keeps them growing and that could damage the plants when cold weather finally arrives. You want them to get cold and stay cold through winter."

Consider amending your soil. Cold injury to plant roots appears more frequently in sandy soils than clay, because cold penetrates deeper into soils with more air spaces.

Provide some insulation. "Tomatoes are a warm-weather plant. To protect them from the first frost, use temporary covers -- sheets, row covers or something similar," Caplan says.

Individual plants can be protected from early arriving frosts by covering them with recycled milk jugs or plastic bottles.

Container plants are particularly prone to frost damage because their roots are unprotected. Wrap them or move them indoors if a cold snap is forecast.

Rake now rather than wait until spring. "Layers of leaves can get wet and pack down the grass, smothering it," Caplan says.

If you weren't satisfied with the look of your flowerbeds, the time is now for transplanting or introducing new plants. You can install your accent plants, perennial beds or spring bulbs and water them well until the ground freezes.

A little procrastination can be good. Potatoes, for example, get starchier and sweeter the longer they stay buried. Brussels sprouts also tend to develop more flavor after a few coatings of frost.

Finally, remember that warm weather often trails the first few frosts. Don't be suckered into fertilizing or composting only to have your plants start blooming again.

"Sometimes, people just get over-excited in the fall," Caplan says. "They want to do something outdoors and then they do more harm than good."

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On the Net:

For more about the effects of cold weather on plants: http://www.agcom.purdue.edu/AgCom/Pubs/HO/HO-203.html

For determining the first and last killing frosts in your area: http://www.victoryseeds.com/frost