Extending the Season with Row Covers
Row covers are lightweight fabric blankets that drape over your plants to trap warmth and hold off frost, stretching the harvest at both ends of the season. They are one of the cheapest, most flexible tools a gardener can own, useful from the first spring planting to the last fall greens.
Row covers are sheets of spun-bonded fabric that let light, air, and water through while trapping a layer of warm air around the plants underneath. They come in different weights: lighter fabrics mainly keep insects off and add a touch of warmth, while heavier fabrics give real frost protection on cold nights. The heavier the cover, the more warmth it holds but the less light it lets through, so match the weight to the job.
In spring, a cover thrown over a new bed lets you plant earlier than the calendar would normally allow, because it buffers young plants against cold nights and drying wind. In fall, the same cover buys extra weeks of harvest from greens and roots by holding off the first light frosts. Many gardeners keep two weights on hand and swap them as the weather shifts.
You can lay the fabric directly on sturdy crops as a floating cover, since they simply push it up as they grow. For tender seedlings or taller plants, support the cover on hoops of wire or flexible pipe, leaving room to grow underneath. Either way, bury or weigh down the edges well with soil, boards, or sandbags, because a cover that blows loose protects nothing.
Ventilation is the part people forget. On a sunny day the space under a cover can heat up fast, so during mild stretches vent or pull back the fabric to keep plants from cooking, then close it again before nightfall. When crops that need bees begin to flower, lift the cover during the day so pollinators can reach the blooms, or remove it once frost is no longer a threat.
Row covers pair naturally with the frost dates for your area. Watch the forecast as your first and last frost windows approach, and have the fabric ready to throw on when a cold night is coming. Stored dry and out of the sun between uses, a good cover lasts several seasons, which makes it one of the best returns on a few dollars in the whole garden.
Frequently asked questions
How much frost protection does a row cover give?
It depends on the fabric weight, but a heavier cover typically buys a few degrees on a cold night, often enough to carry hardy crops through a light frost. For a hard freeze, double up the fabric or add hoops and a second layer, and note that plants touching the cover directly get less protection than those held off by hoops.
Will plants get enough light and water under a cover?
Yes. The fabric is porous, so rain and irrigation soak through and daylight reaches the plants, though heavier covers cut the light noticeably. For crops left covered for weeks, use a lighter weight during mild spells so they do not stretch and weaken from too much shade.
Can I leave the row cover on all season?
You can for crops that do not need insect pollination, like leafy greens and root vegetables, as long as you vent on hot days. For fruiting crops such as squash and cucumbers, open or remove the cover once flowering starts so bees can pollinate the blooms.
General guidance for US home gardens. Conditions vary by region and season; check with your local Cooperative Extension office for site-specific advice. Page updated Aug 4, 2026.