Protecting Plants from Freezing Weather
Plants vary in the amount of cold that they can take in the winter time. Where zinnias are completely killed by a frost, pansies thrive in the cold and will even bloom underneath the snow. Some evergreen shrubs, like jasmine vines, fuchsias, citrus and fragrant rhododendrons, are damaged by severe winter cold, but there are measures you can take to protect these plants.
Keeping plants well-watered is very important in freezing weather. While we’ve had enough rainfall for plants in the ground, container plants are especially vulnerable to the desiccating (drying out) effects of freezing.
There are several ways you can provide winter protection including mulching, covering the plants, moving them, spraying them with an anti-transpirant, or taking advantage of a light snow covering.
Once the soil is moist, mulching is one of the best ways to protect plant roots. A 2-inch mulch will keep the soil from freezing and allow the roots to continue to pull up water as needed. The combination of dry soil and cold temperatures can cause serious freeze damage to trees and shrubs.
Covering plants will protect them from frost damage by trapping the heat that is rising up from the ground. Covering with a plastic tent or ‘Harvest-Guard’ (a lightweight fabric) can make a big difference. If plastic touches the leaves, each point of contact will freeze, so it’s better to make a light frame and staple the plastic to it. ‘Harvest-Guard’ is light enough that you can simply drape it over the plant, but it will need to be secured against winds.
You can also move tender plants to a sheltered location on a porch or underneath an eave or patio cover. It is also less cold underneath trees, so that is also a good spot for more tender plants. Be sure to keep these plants watered if they will not receive rain water.
You can also spray tender plants with an anti-transpirant spray, such as ‘Cloud Cover’, which is made from an acrylic polymer. When sprayed on a plant, it forms a clear, colorless, flexible, glossy film that doesn’t interfere with the plant’s growth. ‘Cloud Cover’ forms a protective coating, holding in moisture on plant foliage and stems, substantially reducing water loss in winter when drying winds and frozen ground deprive plants of their natural moisture intake. It is best to spray in late fall when the temperature is above 40 degrees. The spray will gradually break down in about four months under cold weather conditions.
Mother Nature actually provides the best blanket of protection in the form of a light snow. Up to two or three inches of snow not only insulates the ground around your plants it also provides a blanket of protection over the leaves. On the other hand, a heavy, wet snow can cause considerable damage as it tends to place too much weight on the leaves and branches, often causing them to break. So if the snowfall is wet and heavy, you should make it a point to shake-off the excess snow before any damage occurs. Try to do this carefully so some snow remains as a winter protection.
Each measure gives a few degrees of protection, so try them all on tender plants that you value.