Winter's effect on plants can be surprising. Here are some phenomena you may notice between now and April:
– Bark splitting: Shrubbery and trees growing too vigorously in autumn have excess moisture in their wood, which freezes and causes bark to split if there is a sudden and deep drop in temperature.
– Bending: Snow and ice will bend and disfigure the branches of arborvitae and Leyland cypress. Bent boxwoods spring back to their normal shapes if they are English and American, but columnar boxwoods like Dee Runk may remain permanently bent.
– Breaking: Heavy, wet snow can break the branches of evergreens. Special shelters made of wooden slats are sometimes used to protect prized shrubbery from snow sliding off the roofs of houses. Ice is particularly serious because it increases the weight of tree branches by a factor of 40. A 50-foot-tall evergreen tree going through an ice storm can accumulate 50 tons of ice.
– Dieback: Stems of certain evergreens will die from the tip downward when exposed to severe cold. The winter of 1976-77 was so cold that all of Lynchburg's tree-sized camellias died back to their roots. Bark splitting often leads to dieback.
– Desiccation: Leaf tissues of broadleaf evergreens can lose too much moisture when the soil freezes deeply enough to cut off their roots' ability to provide water. The result is a browning around the edges of leaves called winter burn and marginal scorch on susceptible plants like magnolia, holly, rhododendron, camellia and nandina.
– Discoloration: The rich green color of evergreens and lawns fades away when conditions turn extremely cold. Normal color returns in spring.
– Hardy: A plant is hardy if it can tolerate cold. As a rule, leaf buds are hardier than flower buds and stems are hardier than roots. Plants growing in pots outdoors are less likely to survive the cold than those growing in the ground where their roots are insulated by soil.
– Leaf roll: You can tell that it is really cold outside by looking at rhododendron and Japanese aucuba. Under low temperatures, their broad evergreen leaves droop and roll up to conserve moisture.
– Mulching: Spreading a layer of mulch over your plants' root zone will insulate the soil and conserve moisture.
– Rodents: Mice and voles may damage bulbs, roots and stems in winter. Excessive mulch encourages rodent activity.
– Sapsuckers: These members of the woodpecker family migrate through our region in winter, feeding on trees and shrubs as they go. Their injury ranges from a harmless ring of small holes around a tree trunk to a more serious checkerboard pattern of torn bark.
– Sunscald: Rapid temperature changes on a sunny and cold winter day may cause bark to die on the southwest side of a cherry, apple or red maple tree's trunk. You can prevent it by putting plastic trunk protectors on newly planted trees to shade their bark. Gardeners have also been known to coat tree trunks with white latex paint for the same reason.