A floating row cover is a thin white material made of polypropylene or polyester that has multiple garden uses. They come in various weights and sizes depending upon their intended use. The lightest weight products, used to protect plants from pests, allow about 95% of sunlight through and don’t trap heat so they can be left in place all season.
Heavier covers intended for frost protection allow less sunlight to penetrate. Using two layers provides even more protection, giving plants up to 10ﹶF of extra warmth. They can be used to extend both the beginning and the end of the gardening season to allow more time for growth and harvest. Frost protection covers should be removed on warm days to prevent excessive heat buildup.
For both frost and pest protection, the edges need to be held down with soil, bricks, stakes or pins sold especially for floating row covers.
Another use for the covers is to protect newly planted seedlings from transplant shock. Several days of partial shade and wind protection followed by removal of covers on a cloudy, still day can substitute for time consuming hardening off where plants are moved from sun to shade and back again several times a day for a few weeks to acclimate them to harsher garden conditions.
The covers can also provide shade to prevent leafy greens like lettuce and spinach from bolting in the heat of early summer. In this case, the edges don’t need to be held down, but some kind of structure will be needed to hold the cover above the crop. Similarly, floating row cover shade can provide a few degrees of coolness necessary when starting late summer crops for fall harvest.
When used for pest control, covers can stay in place all season for self-pollinating plants like bush beans, leafy vegetables and root crops. Plants that need insect pollination such as squash, pumpkins, zucchini and cucumbers need to have their covers removed or opened at the ends to allow pollinating insects to access their flowers, or you could hand-pollinate.
Keep in mind that many insects overwinter in soil, so check under the covers often to make sure you haven’t inadvertently provided a nice cozy buffet for the very insects you are trying to exclude.
If plants are going to be under cover for any length of time, it’s best to build a support structure to allow for plant growth, increase airflow and avoid damage caused by unsupported fabric flapping in the wind.
Although I’d prefer to see and touch the floating row cover before I buy, this year I’m not willing to go from store to store to shop. Websites for local big box stores and garden centers turned up no results for floating row cover, and an Amazon search led to several hundred results which was too many to sort through. In the end I decided to go with what was offered at one of the mail order nurseries that I trust.
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