While it’s true that plant dormancy mitigates much of the damage done by winter weather, it’d be wrong to assume our gardens are invincible during this time. Among the most common plagues plants face is what’s known as winter desiccation. Even harder to prevent than it is to spell, desiccation—in its simplest form—is an excessive drying out of plants occurring when more water evaporates from leaves than is sucked up by roots.
This predicament affects any plants whose foliage remains over the winter, i.e. evergreens such as boxwoods, rhododendrons, hollies, hemlocks, or pines. For them, replacing water lost by leaves on sunny and windy days is next to impossible, as dry, frozen soil doesn’t provide sufficient moisture to the roots. The result of this is browning foliage and needle drop, with your broadleaf evergreens (rhodies, skip laurels, hollies, etc) experiencing a higher propensity for damage than their needle-leafed counterparts.
During or after the last two winter seasons, both especially harsh, you may have noticed plants experiencing these symptoms. But don't be led to believe they're off the hook because of this year's unseasonable warmth. Between now and the last frost--unless it's pina colada weather each day--you can expect to see the effects of desiccation once again. Fortunately, it's not a death sentence for your plants. There are still precautions you can take to prevent significant damage from happening!
One common preventative measure is to thoroughly soak the root zone of any evergreen (especially young or unestablished specimens!) in the fall before the soil freezes, which will assure the plant begins the season with adequate moisture levels. Another is to apply an anti-desiccant spray to the foliage of potentially affected plants, which will help prevent any damage that does occur. If you missed your opportunity to do these things in Fall, don't dismay. During any of the warmer days we're bound to experience again this winter, you can apply these techniques and greatly improve the chances of plant survival.
While it should be noted that these preventative measures are hardly “magic bullets,” they can go a long way in protecting your trees and shrubs from harm. At Terren, we offer anti-desiccant spray services for small trees and shrubs, as well as watering advice to all of our customers, which we’ve found really pays off for many of them. If you’re in the area and interested in the service, contact us anytime to set it up. If not, check your local garden supply store for companies in your area or DIY materials.
In any case. Good luck!
Zinati, G., A. B. Gould, R. Buckley, and R. Obal. 2006. Landscape and Ornamental Plant Stress: Factors, Symptoms, Diagnosis and Management. Rutgers Cooperative Research and Extension. E309.