Floating row covers are handy items for gardeners in any climate. Floating row covers are lightweight spunbonded white fabric made of either polyester or polypropylene. They are most often used to protect plants from a light frost, but they have uses for gardeners in warmer climates too.
Floating row covers can be used not only to extend the gardening season but also to protect plants against destructive insects and marauding deer, groundhogs and rabbits.
When a light frost is expected in either spring or fall, floating row covers can be draped over plants to help hold in warmth from the ground, protecting your plants from freezing. A lightweight row cover will give 2-4 degrees of temperature protection for your plants, while heavier row covers will provide frost protection in temperatures as low as 20 degrees. When used in the spring, floating row covers allow you to start your garden up to two weeks early.
A heavier floating row cover that is used mainly for cold protection is sometimes referred to as a frost blanket. Frost blankets would not be used to protect plants from insects and animals, as the more substantial fabric does not allow as much light to pass through to the plants. Frost blankets are ideal for getting a jump start on the garden in the spring and for protecting plants in the fall.
Sunlight and rain will both pass through the floating row covers to your plants, so the fabric can be left on the plants as needed. Since the fabric is so lightweight, any breeze will send it drifting away if it isn’t anchored down. Install floating row covers on a calm day to make the job much easier, then secure the edges of the fabric to the ground with stones, boards, piles of soil, or wire earth staples. Earth staples are simply U-shaped wires that are pushed through a folded edge of the fabric and into the soil to hold the fabric securely to the ground. You can purchase earth staples at garden centers or from gardening catalogs, or you can make your own out of old wire clothes hangers.
If the floating row covers are to be draped directly over small plants in the garden, be sure to not stretch the fabric tightly across the plants. Allow some slack in the fabric to give the plants room to grow without pushing up their warm blanket.
To protect tall transplants such as tomatoes, or when protecting plants from an early frost late in the season, you may wish to use support hoops to keep the floating row covers off the plants. Either wire or bamboo support hoops will do the job nicely. When using support hoops beneath the floating row covers, the fabric should be stretched taut over the hoops and secured to the ground to prevent wind from catching it and blowing it off the plants. Use binder clips or clothespins to secure the fabric to the hoops for added wind protection.
Floating row covers make good barriers against hungry animals that want to eat your plants. Foil the neighborhood deer and rabbits by draping floating row covers over tender young plants until the plants are a bit older and not as desirable for critter meals. Lightweight floating row covers are the best for animal barriers as they allow eighty percent or more of the sunlight to reach the plants through the fabric.
If animals are a continuing problem in the garden, the floating row covers can be left on most plants indefinitely, but as the season progresses and the weather warms, the plants should be watched for signs of overheating as the row covers trap warm air beneath them. If the plants are showing signs of heat stress, remove the row covers during the day for ventilation and replace them in the evening before the animals venture out for dinner.
Floating row covers can also prevent insects from attacking your plants. This is particularly useful for vegetable crops such as broccoli or squash. If the butterflies can’t lay their eggs on your plants you won’t have any of their little green worms hiding amongst the broccoli florets. Similarly, squash bugs can’t reach squash plants that are nestled beneath floating row covers. But make sure to remove the fabric from the plants when they begin to flower so pollinating insects can reach the blossoms. Plants that need insects for pollination include squash, melons, cucumbers, peas, beans and strawberries. Lift the floating row covers off of these plants during the day while they are flowering and pollinators are active.
Root crops and greens, along with plants that are self-pollinating such as tomatoes and peppers, can be kept beneath row covers all season if need be. But again, watch the plants for signs of overheating on warm days. When the air temperature is above 85 degrees, tomato pollen becomes sterile and peppers will drop their blossoms without setting fruit. On extra-warm days, allow some air ventilation beneath the floating row covers to help these plants keep their cool.
Some garden insect pests will overwinter in the soil and could be trapped beneath the floating row covers that are meant to keep them out. Flea beetles that attack radishes, broccoli and other leafy crops will overwinter in the soil, along with tomato hornworms, potato beetles and root maggots. A simple way to foil these pests is to rotate your crops so when these pests emerge in the spring, they find that their favorite foods are now growing in a different section of the garden, safely tucked away under floating row covers.
Floating row covers and frost blankets are available in garden centers and gardening catalogs. The fabric comes in a variety of widths and lengths, and can be purchased in lengths long enough to cover an entire row of plants. The fabric can also be easily cut to size for protecting individual plants. If used and stored carefully, the fabric can last for several years. When it’s not in use, fold your floating row covers and store them in a dry area out of the reach of rodents that may want to use it for nesting material.