If you’ve ever looked into season-extending options to help grow in early spring, mid-summer, and into winter, you know that row covers are the key to a successful harvest. It can be hard to imagine how just a few millimeters of fabric or plastic sheeting can protect your plants, but choosing the right row cover can help your plants survive cold, heat, hail, and insects. It makes a big difference.
Row covers are typically made of two types of materials: polyethylene plastic or spunbond fabric (such as polyester or polypropylene). They come in different thicknesses and weights to suit different needs and climates, and the one below is what I’ve used in my own garden.
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polyethylene plastic cover
Polyethylene plastic coverings (also called greenhouse plastics or greenhouse films) are commonly used for greenhouses, high-rise tunnels, and low-rise tunnels. Many are UV-treated for added durability, but if you’re on a budget, you can also use plain construction-grade plastic sheets sold at hardware and home improvement stores.
Clear plastic generates and retains more heat than fabric, so it can protect more tender plants in the winter. However, the rapid rise in temperature makes it difficult to manage, especially in climates with large temperature fluctuations. Whether it’s a sunny day or a 40-degree Fahrenheit day, lack of ventilation can have a negative impact on plants inside a plastic-covered tunnel. Therefore, some plastic covers are perforated to improve temperature control.
spunbond fabric
Spunbond fabrics are used for frost protection in low tunnels (hence why they are sometimes called frost cloths, frost blankets, frost covers, or simply garden fleece). It’s not a cloth-like material as you might imagine, but a very light web made of poly fibers bonded together. It is permeable to water and air, allowing rain to pass through and natural ventilation.
Frost cloth is available in weights measured in ounces per square yard. This not only indicates the degree of frost protection, but also how much sunlight it lets in. When growing plants in the winter without a greenhouse, I usually prefer medium-weight frost cloth. This provides a good compromise between insulation (typically provides about 5°F of cold protection) and light transmission (about 70%, useful when winter sunlight is already very limited). It’s a compromise.
Can you use bed sheets and other fabrics as frost protection? In a pinch, yes. However, actual frost covers are designed to dry quickly and provide adequate airflow to protect your plants without risking damage.
If you’re growing cold-hardy vegetables suitable for your climate, a medium-thick cover will often provide sufficient insulation from late fall to early spring. You can always double the dough for polar vortex days. If you want to overwinter the container, you can step up to thick frost cloth or extra thick frost cloth.
I personally use Agribon, which is the industry standard and comes in rolls. If you go with a different brand, be sure to check its weight to know how much cold protection it actually provides.
floating column cover
Floating row covers are very lightweight covers that protect against pests, especially early in the season. There is no need to build frames or tunnels, as the material “floats” directly above the plants and is secured with landscape pins, rocks, or bricks. The plants below will support the floating row cover and push the cover up as it grows.
It is important to use a floating row cover over your bed before you think you will need it. Consider the time from late winter to mid-spring to sow seeds or transplant seedlings. Otherwise, there is a risk that insects will become trapped under the cover and will not have a way out and will breed.
Lightweight spunbond fabrics are often sold as floating row covers. You can also use thin white tulle or organdy from fabric stores as insect repellent.
Insect net
Insect nets do not retain heat. A soft and flexible window screen that looks and feels soft and comes with a variety of mesh opening sizes to accommodate a variety of insects. In general, the smaller the openings in the mesh, the better because it will exclude more insects, but the denser the mesh, the less light will pass through and the more heat will accumulate.
So what is the difference between an insect net and a floating row cover? When it comes to use, it’s mainly about durability. Insect nets can last for several years if stored properly, but floating row covers and lightweight fabrics are usually very delicate and may need to be replaced every few seasons.
Bird net
Bird netting has wide mesh openings that are large enough for some insects to pass through, but large enough to prevent birds (and other small pests such as rabbits) from gnawing on the soft grafts. is small enough. Bird netting is also good insurance for newly planted seedlings.
Depending on the type of bird netting, there are some that are so fragile that they tear right out of the package, while others that are durable enough to withstand several seasons, so the quality can vary widely. I did.
shade cloth
Shade cloth is another type of row cover used to block some sunlight in the summer. Usually it’s a dark, loosely woven poly (with mesh openings that are somewhere between insect screen and bird screen) in a low tunnel, tomato cage, or other structure to provide shade for the plants. Hang it on top.
This will help you grow lettuce in the summer and prevent tomato flowers from falling. Depending on what you’re growing and the size of your plants, you don’t need to cover the sides of the entire bed with shade cloth. They can be installed like canopies in low tunnels to shade plants during the hottest parts of the day.
This depends on your climate, but using a 30% to 40% shade cloth will provide enough heat relief without blocking out too much light.
hail net
Hail netting is typically made of high-density polyethylene mesh that can withstand hail damage. The fibers are woven in such a way that they maintain their shape even when hit by hail.
If you live in an area where summer hailstorms are common, this is a great row cover to have in your collection so you don’t lose your crops. However, if you only get a small amount of pea-sized hail, a regular cloth cover is fine.
How to use the row cover
Most row covers are used over low tunnels. You can build simple, inexpensive, low tunnels using PVC pipe, EMT conduit, or galvanized steel wire (like this 9-gauge wire, which can be cut to size). Bend the pipe or wire into an arc (a “hoop”) to fit the bed, stick the end of the hoop into the ground, spread the cover over the hoop and secure with clips or clamps.
Low tunnels are typically 2 to 4 feet wide and at least 18 inches high. (My own low tunnels are 4 feet tall to accommodate larger plants, as the garden often experiences frost in late spring and early summer.)
You can also purchase a low tunnel kit that comes with pre-formed hoops or connectable hoops. Some of them (like the Easy Tunnels linked below) have a fleece or poly cover permanently attached to the hoop. The entire tunnel folds up like an accordion, making it quick and easy to cover plants on the spot.
