Can I Use Old Carpet to Cover Cold Frames?

Extra Insulation for Frigid Nights

• A piece of old carpeting large enough to cover the entire surface of the cold frame is often cited as a good material to use when overnight lows threaten to dip close to freezing. Because the interior temperature of a cold frame is usually only several degrees warmer than the ambient temperature, tossing a carpet over the frame can retain enough essential warmth that the plants and soil inside the frame won’t freeze. Additionally, strips of carpet stapled or glued to the edges of the sash frames, like the furring strip on the bottoms of windows, insulate areas where air tends to escape.

Putting On, Taking Off

• When temperatures are forecast to plunge overnight, put carpeting or other insulators over the cold frame before the sun goes down to retain solar warmth for the night. Keep the cover on the frame until the air temperature the next morning rises. If daytime temperatures stay low, leave the carpet in place. Plants tolerate several days of darkness but do not survive exposure to killing cold temperatures.

Other Materials

• Many other items can be used in lieu of a piece of carpet, as long as they provide uniform coverage and can be easily put on and taken off. Lightweight straw bales, bags of leaves, evergreen boughs, thick blankets or several layers of spun-poly row cover work to provide additional temporary insulation for cold nights. Straw bales and bags of leaves can be piled up against the walls of a cold frame all winter long to bolster insulation and defend against heat loss.

Precautions

• While thick plastic panels have the advantage of being tough to break, other materials often used in cold frames aren’t always so resilient. Glass frames, especially those built with single-paned windows, can easily crack or shatter if subjected to a sudden thump, such as when a length of carpet is plunked down. Plastic sheeting can warp or stretch when manhandled. Slide the carpet carefully over the frame to reduce the stress on the cover of the cold frame. Also, brush off snow or ice accumulations on the cold frame and any insulating covers; the additional weight may crack or damage the cold frame lids.