Newswise — If gardeners are concerned that this year’s record snowfall will harm their dormant plants, fret not, says botanist Karen Snetselaar, Ph.D., chair and professor of biology at Saint Joseph’s University in Philadelphia, Pa.
“Snow cover is actually beneficial for many plants, especially perennial herbs and shrubs, because it provides insulation from freezing temperatures,” notes Snetselaar. “Plants under snow will be exposed to fewer drastic temperature changes, which is often more damaging than continued cold.”
Though we may pine for them in the depths of February, uncharacteristic warm days that offer a break in the weather are bad for gardens, according to Snetselaar. “Early-blooming forsythia bushes, magnolia trees, daffodils and tulips may look pretty, but when cold weather inevitably returns, they may be damaged.”
Snetselaar adds that, in recent years, even some cherry trees and other plants that normally do not break dormancy early have started flowering long before they should because of extended periods of warm weather early in the season. “This year the deep snow cover has kept it cool around the plants on warm, sunny days, so I would expect that we’ll see less of this potentially damaging early bloom.”
Another benefit of snow, especially around broad-leaved evergreens like rhododendrons, is that it can help keep moisture around the plants and perhaps reduce airflow, Snetselaar says. “Oftentimes, winter damage to these plants is more about dry winds than about freezing temperatures. Cold air can’t hold as much moisture as warm air, and when very cold air blows over the leaves, it draws moisture from them. It’s always a good idea to be sure that evergreens go into the winter well-hydrated.”
However, there are some unavoidable hazards to trees associated with this year’s “snowmaggedon” season. One highly visible problem is branches over-burdened with snow. Snetselaar says during snowstorms, “Take extra care of evergreens.”
“When there is heavy snow, gently brush it off, pushing the evergreen’s branches up, not down,” she advises. “This can help minimize broken branches, but it is important to be careful, because the branches are quite brittle when it is cold.”
What should be done when a tree has a large broken branch? Snetselaar suggests consulting an arborist for very large branches or for especially valuable trees. Limbs that are partly broken or that may pose a danger should be pruned or removed right away.
“Use good pruning practices, cutting branches back to sound wood and leaving a ‘collar,’ which means to cut close to, but not too close to the trunk or larger branch, to facilitate wound healing,” she recommends. “However, it’s best to wait before pruning shrubs or trees that are bent or misshapen after heavy snow. Some may gradually straighten up and be fine. And obviously, don’t attempt to remove any branches that are near overhead wires. Leave those to the utility company.”
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