By By Charlie Nardozzi, National Gardening Association
The first frost isn’t necessarily the end of the harvest season. If you’re growing cool-season crops, such as lettuce and broccoli, or trying to tease the last few vegetables from warm-season crops like tomatoes, you can protect them to extend the harvest window. Here are some different types of coverings that can keep your veggies producing well into fall – in some cases, even after the snow flies.
Sheets, Tarps, Buckets Drape fabrics over plants, making sure they touch the ground to hold in the heat around the base of the plants. You can also place plastic buckets over choice plants when frost threatens, then remove them the next morning.
Floating Row Covers Made from lightweight, spunbonded polyester or spunbonded polypropylene fabric, floating row covers are loosely laid over plants and anchored down with soil, stones, or wire stakes. They allow the sun, rain, and air to reach plants, yet protect crops when temperatures drop into the high twenties. They come in different thicknesses; the thinnest ones won’t protect against frost, but the heavier ones can protect plants down to about 28 degree F.
Grow Tunnels
Grow tunnels are made from row cover fabric stretched over a metal or plastic frame. Some grow tunnels have slits allowing for natural venting so plants don’t overheat, but these don’t offer much protection against the cold. The thickest grow tunnel fabrics protect plants down to about 26 degrees F.
Cloche
Shaped like a bell or dome, cloches are usually made of plastic or glass. You can purchase fashionable glass ones, or make your own by cutting the bottom off a plastic gallon milk jug and setting it over a plant. They’re great for protecting individual plants, such as basil. Some cloches are airtight, offering more frost protection, but these need to be removed during sunny days so plants don’t overheat. For less maintenance, choose cloches that are vented on top. They won’t protect plants from freezing temperatures as well as closed cloches, but plants are less likely to be burned from excessive heat during the day.
Cold Frame
A simple, homemade cold frame can be constructed from a 3-foot-wide by 6-foot-long wooden box, or even by hay bales arranged in a box shape. Place an old window sash, piece of translucent plastic, or plexiglass on top. More elaborate prepackaged cold frame boxes are made of fiberglass, metal, or wood, and some have automatic vents. The best location for your cold frame is a south-facing, protected spot, such as the side of a garage. You can use this box to shelter potted plants, or plant directly into the soil inside the box after amending it well with compost.
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