Plant Covers for Winter

Keep your plants safe from frost by using winter plant covers. These chill-chasing covers give plants a cozy hideaway that’s warmer than surrounding air. The difference is often only a few degrees, but those degrees make a big difference. Protecting plants from freezes isn’t difficult.

One of the most common winter plant covers is a frost blanket or floating row cover that you toss over plants before a freeze arrives. Frost blankets work by excluding cold air and creating an insulating air pocket around plants. Heat from soil, which is warmer than air, is trapped beneath the blanket and held near plants.

These cold-defeating fabrics are made from a woven polypropylene that’s lightweight and breathable. The material allows sunlight and water to reach plants, but keeps frost out. Most of these winter plant covers are also UV-stabilized. This means the materials won’t break down quickly when exposed to sunlight and can be used for several growing seasons.

Frost blankets come in varying thicknesses. Thicker blankets protect plants to a greater degree than thinner ones. Thicker blankets also exclude more light. Thinner frost blankets typically protect plants to 28° F and permit 70 percent of sunlight to reach plants. Thicker blankets protect plants from 24 to 26° F and allow 30 percent of sunlight to reach plants. It’s most economical to purchase frost blanket rolls 20 to 100 feet long, 6 or 12 feet wide. Cut the fabric into custom sizes, and sew pieces together as needed to form larger blankets.

Although frost blankets can lie directly on plants, you’ll get the best protection when you create a framework that holds the winter plant covers above plants. Build a temporary or permanent framework using flexible PVC pipes slid over pieces of rebar driven into the ground. Or drape the blanket over short wire garden fencing. Using materials you have on hand is the secret to creating an inexpensive support system.

When using a frost blanket, be sure to anchor the edges to exclude all cold air. Hold edges down with landscape pins, bricks, lumber or other available materials. Or bury edges in a shallow trench, anchoring them with soil.