GardenSMART :: Winter Burn on Broadleaved Evergreens
Winter Burn on Broadleaved Evergreens
By Therese Ciesinski, GardenSMART
We’ve all seen brown, limp, or crispy leaves on broadleaved evergreens in winter: shrubs such as rhododendrons, azaleas, boxwoods, hollies and laurels. Or the curious sight of rhododendron leaves rolled into cigar shapes. The former is damage caused by cold, dry, windy weather. The latter is the plant trying to protect itself from those same conditions.
All plants release moisture through the pores on their leaves. It’s called transpiration, a normal year-round process. When it’s cold, dry, and windy, especially if there’s not enough moisture in the soil, leaves, particularly on broadleaved evergreens, will lose moisture faster than the roots can take it up. Call it winter burn, sunscald, windburn, or desiccation, it can cause irreversible and disfiguring damage to a plant, and even kill it. At best the plant is stressed, and flowering and overall vigor are adversely affected.
Anti-desiccants are oil- or polymer-based sprays that can help seal the pores on leaves, reducing moisture loss and preventing damage. You may also hear them called antitranspirants. Wilt-Pruf and Bonide are two brands. Used properly, they won’t harm plants. Used improperly they can, so if you decide to try an anti-desiccant, first read the label.
Apply on a dry day when temps are between 40 and 50 degrees, and there’s no rain or below-freezing temperatures forecast for the next 24 hours. Spray both sides of leaves. Protection won’t last the entire winter; you may have to reapply a few times a season.
A smarter – and less labor intense – solution is to choose plants that don’t need to be protected in the first place. Select plants that are known to be cold hardy in your area, site them in the right location for their needs, and make sure they get adequate moisture throughout the growing season and during drought, especially if they’ve been planted within the past year. You can also cover the root zone with two to three inches of mulch once the soil freezes. Winter weather can be harsh, but with care, it doesn’t have to take a toll on your broadleaved shrubs.
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By Joan Casanova, Bonnie Plants,
Photographs courtesy of Bonnie Plants
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