Cold temperatures and late winter snow 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.
“Trees already in flower, such as the Cherry, Red Maple, American Elm or Bradford Pear, 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 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 stemmed evergreens can be tied together temporarily to prevent bowing and breakage. A long broom or extension poles can also be used to gently knock off snow accumulations 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 others, like 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. Dormant season pruning of deciduous woody plants can be done earlier but, 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,” says Conrad.