Expert offers tips for protecting trees, plants from late cold snap

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Cold temperatures and late winter snow can place many types of trees and plants at risk, says Virginia Cooperative Extension agriculture expert Kirsten Ann Conrad.

“In the Mid-Atlantic region we typically do not have reliably frost free weather until at least mid-April and even then we can be surprised with a late frost. Flowering trees and evergreens particularly will suffer from a late winter cold,” says Conrad.

Quoting Conrad

“Trees already in flower, such as the Cherry, Red Maple, American Elm and large leaved evergreens like Southern Magnolia, will trap snow and ice on their branches, buds and flowers.

“The extra weight that is trapped by the flowers and buds that are open or nearly open in very early spring can result in breakage. On evergreens, the extra weight of snow can cause multi stemmed evergreens such as Arborvitae to bow outwards and or to snap off.” 

“In cases of heavy snow, go out periodically and shake off snow accumulations to avoid breakage of smaller trees and shrubs. Multi-stem evergreens can be tied together temporarily to prevent bowing and breakage.

“A long broom or extension pole can also be used to gently knock off snow accumulations of lower branches of pines in order to avoid buildup.” 

When it comes to cold temperatures spring flowering trees can sustain some damage to the flower and leaf buds, Conrad says.

“Cherry trees and most flowering ornamentals will avoid extensive damage as long as the temperature stays above 26-27 degrees. Less than that, the damage increases proportionately. Up to 90 percent of cherry blossoms in late bud or flowering stage will be damaged at temperatures that go down to 24 degrees Fahrenheit.”

“Herbaceous plants, especially the perennials and bulbs that are emerging now, are pretty hardy. Daffodils can withstand temperatures down to 20 degrees and many other perennials, though they might get a little brown on the edges of their leaves, will suffer no permanent damage.

“Covering over hardy vegetable crops and perennials with a light cover like a sheet or woven cloth can provide 4-6 degrees of frost protection.”

“Shrubs, like some hydrangeas that are marginally hardy here and roses, which are already leafing out, have a risk of tip dieback from extreme cold. This is also true for new growth on evergreens that is stimulated by improperly timed pruning,” says Conrad.

“Winter pruning of deciduous woody plants should be done when plants are truly dormant and gardeners can avoid winter burn to new tender growth of leafy evergreens by ensuring that pruning is done after the threat of extreme cold has passed.” 

You can view more gardening tips by visiting the Cornell Cooperative Extension website at www.cceoneida.com or by calling our Horticulture Hotline at 315-736-3394, 9 a.m. to noon on Wednesdays and Fridays.

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