Row covers for gardens are lightweight fabrics you drape over plants to shield them from frost, bugs, and harsh wind. Most are made from spun-bonded synthetic fibers that let in sun and rain at the same time. These covers form a thin barrier above your crops without blocking the things your plants need to grow. You can buy them in different weights at most garden stores or order them online for less than ten dollars per pack.
I have used a floating row cover in my own beds for five seasons now and the gains shocked me. My spring spinach came in three weeks sooner than my uncovered beds did. I tested fall kale under cover and the plants kept growing into November when bare beds had already frozen out. My summer broccoli also dodged the worst of the cabbage moth damage that ruined my crops back in my first year.
The fabric works because tiny fibers cross over each other in random patterns and scatter the light. Heat from the soil gets trapped under the cover at night and warms the air around your plants. Air and water still flow in and out as needed. Bugs cannot crawl through the tight weave on top, so your leaves stay free from chew marks and egg clusters.
Cover weight changes how much sun gets through to your plants below the fabric. Per Maryland Extension, light covers transmit 90 to 95% of sunlight. Medium covers let through 70 to 85% of light. Heavy frost blankets cut light to just 30 to 50% of full sun. Match the weight to what you want the cover to do for you that month.
I use the lightest grade over my seedlings in spring when I want them to soak up sun. When frost moves in around late October, I switch to a heavier garden fabric that traps more warmth at night. You should keep a few weights on hand so you can swap them out as the weather shifts in your area.
Cabbage and broccoli love covers because the fabric keeps cabbage worms and flea beetles off the leaves. I learned this the hard way after losing a whole bed of kale to flea beetles in my first year. The tiny black bugs put holes in every leaf within just a few days. Warm weather hit my garden and the damage spread fast. A cover would have saved that whole crop with no fuss at all.
Cucurbits such as squash and cucumbers stay safe from vine borers when you cover them from day one. Salad greens get a real boost too since the spun-bonded polyester holds in soil moisture and softens the strong summer sun. Lettuce stays crisp and sweet when shaded a bit during hot weeks.
Pull covers off flowering crops though, because bees need open access to set fruit on your plants. Leaving fabric on tomatoes or peppers during bloom will cut your harvest down hard. I made this mistake my second year and got just three peppers from a bed of six plants that should have given me dozens. Time your covers right and you will see a big jump in both yield and plant health.
Read the full article: Row Cover Garden Guide: Weights and Timing
