Published on 01/05/99

Get a Jump on Early Garden With Cold Frames, Hot Beds

Georgians can look forward to a growing season of 165 to 230 days or more. However, most of us become anxious to get started before the last of winter's cold is gone.

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Modern plastic cloches provide about the same protection as traditional straw or pottery.

Historically, gardeners have taken early transplants safely outdoors before the weather is ready in a number of ways.

Bell-shaped cloches made from pottery or woven straw for night protection in milder climates can be traced to 1629 in Britain and even earlier in France and Europe.

Cold frames and hot beds are both bottomless boxes with a clear glazing or covering to let in light. The difference is that the hot beds include a buried layer of manure to slowly decompose and keep a higher temperature in the enclosure.

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Cross-section of a hotbed.

These enclosures help ease seedlings from the indoor window to the outdoor garden. However, you can use them, too, for an early-spring or late- fall vegetable crop, or for a winter garden.

Given enough moisture and fertilization, most fall- planted cool-season crops will keep growing through early winter in the cold frame.

Depending on the harshness of the winter and whether you use added heating, your frame can provide fresh greens, herbs and root crops all winter.

Lettuce, spinach, radishes, green onions or other cool- weather crops will thrive in the cold frame. Straw bales make effective insulation in the coldest part of winter. Another way to keep the structure warm is to keep several light bulbs burning during the extreme cold.

Unheated frames are useful for much of the year because they collect heat from the sun through the panes.

To make the most of the heat and light, put the cold frame in a southern or southeastern exposure with a slight slope for good drainage. A sheltered spot with a wall or hedge to the north will protect against winter winds.

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Water-filled tubes store solar heat and provide frost protection.

Modern technology has greatly expanded the options the gardener has for extending the growing season. The latest design in cloches is circles of water-filled, plastic tubes to collect solar heat and provide further frost protection.

The idea of cloches has also been combined with the idea of cold frames into tunnels of solid and slit plastic or fiberglass that cover entire rows but can be removed as the season progresses.

The newest tools are floating row covers. These lightweight, spunbonded fabrics drape loosely over rows so they can be raised as the plants grow.

Floating row covers offer about 4 degrees of frost protection. But they're most valuable as they protect plants from drying winds, boost daytime temperatures under the cover, and provide excellent protection, if properly installed, from flying insect pests.

To get the latter, you have to cover the edges with soil or firmly attach them to raised beds so the insects can't get in. Then you can have pesticide-free, wormless broccoli earlier and healthier than ever before.

No special ventilation is required with these new row covers. Water seeps right through. With care, you can remove, store and use the covers for two growing seasons.

Wayne McLaurin is a professor emeritus of horticulture with the University of Georgia College of Agricultural and Environmental Sciences.