Extended periods of below-freezing weather are rough on us and our pets but these aren’t the only victims-trees and shrubs in the landscape can also take a beating from extreme cold. One or two days where the temps don’t rise above freezing are not usually damaging to plants but when we start to see several days or longer of below freezing, the situation gets much more serious.

Several things can happen when extended cold is present. First, shrubs and trees suffer from lack of water. Plants do take up water during the winter and when the ground is frozen, the water is not available. Also, cold, drying winds can pull moisture out of plant tissues. This is called desiccation. Then when the plant is unable to pull moisture from the soil, it can suffer damage or death from the lack of water. Sprays are available to apply when long-term frigid temps are expected. These sprays coat the plants and prevent moisture loss.

Spray Plants to Prevent Moisture Loss

Burlap wraps and extra mulch are also useful in cold protection of plants. White latex paint applied half-way up tree trunks provides protection against splitting. Never, ever wrap plants in plastic. Plastic is not breathable and traps moisture, which freezes and causes more damage. It is also important to water landscape plants when temperatures get above freezing. This gives the plant an opportunity to take in some water before the thermometer plummets again.

Photo: Barbara Ellen Koch

Earlier actions can also affect a plants’ winter-hardiness. Fall fertilization of trees and shrubs can prevent tissues from hardening off and going dormant. When freezing weather hits, the sap in these plants expands and freezes and causes bark split. This is why we don’t recommend fertilization of trees and shrubs later than mid-July. Shallow rooted shrubs such as azaleas should be watched carefully when the ground begins to thaw. Heaving of icy soil can expose fragile roots.

Flower and fruit buds are always in danger when super cold weather moves in. Leaf buds fare a little better and rarely suffer damage. But be prepared for the lack of hydrangea blooms when late spring freezes occur. They seem to be greatly affected by freezing temperatures.

Even if cold temperatures have been in our area for a few days, you can still protect plants with wraps and water whenever possible. Do not attempt to prune anything unless there is breakage. Leave damaged wood in place to give protection until spring. When damage is seen in the spring, don’t give up immediately. Give plants a chance to recover before getting rid of them. Ultimately, the best way to protect landscape plants is to use those that are hardy for our area and by planting them in the proper place.

Cover Plants with Cloth – Not Plastic