Snow can cause damage when it is thrown over plants by shoveling or snowplows. Snow pushed or thrown over plants is denser than natural snowfall and can rip branches from shrubs and small trees. Evergreens, which trap snow, are most susceptible.
Immediately after a snowstorm, gently remove snow from branches that are bending to the ground. Most evergreens bent over by winter snow recover their upright shape in spring. Do not try to crack ice off branches. Wait for it to melt.
Snow can be good for the landscape because it is an insulator against chilling temperatures. Snow on the ground prevents injury to roots, which generally can't withstand extreme cold. Snow gradually melts and waters the plants during the winter.
Salt injury
Salt draws moisture from plant cells, causing tissue to dry out. This can happen in roots or leaves. Needled and broadleaf evergreens are most susceptible to salt damage because they still have living leaves.
Salt damage on deciduous plants like oak and dogwood trees is different. The salt may produce scorched leaf tips and margins in spring.
Prune wisely
Winter weather conditions can be especially rough on leaves. Southern magnolia, American holly, nandina and boxwood are often damaged.
Cold temperatures and drying winds are responsible for damage on many plants. Just because the leaves are brown or droopy does not necessarily mean that the branch is sick or dead. Most shrubs recover and produce healthy foliage in spring when damaged leaves are quickly masked.
To check for damage, use your fingernail or a small knife to look for green tissue under the bark. Dead-looking branches often will be green underneath, so just check.
Another way to check for injury is to bend the dead-looking branch. If it snaps off quickly, it is really dead. If it bends, there may be hope.
Don't prune damaged branches before spring dormancy breaks. Healthy flower buds near the dead area also will be cut off. Then there will be no flowers at all.
In some cases, plants look just fine, then in spring they all suddenly begin turning yellow or brown. This indicates that the root system was frozen and damaged during the cold weather. There is nothing that can be done at this point.
Sun and wind
Winter sun and wind can cause excessive water loss of evergreen trees and shrubs. Limbs will often turn brown. This also can occur when temperatures warm up on sunny days then drop quickly at night. Winter injury occurs more frequently on the south, southwest and windward sides of the plant.
Yew, arborvitae and hemlock are most susceptible and should not be planted in windy or sunny exposures. Reduce damage by propping pine boughs against or over evergreens as insulation.
Bark on some trees may split on the southwest side due to rapid temperature changes. Thin-barked trees such as maples, lindens and cherries are most likely to crack. Tree wrap may give protection. There are several wraps that can be put on for the winter then taken off in the spring.
Mulching in fall can help insulate roots from winter damage. A 4-inch layer of mulch or compost helps protect plants in the winter.
For care of storm-damaged trees see www.utextension.utk.edu/publications/spfiles/sp575.pdf
Contact Tom Stebbins at tstebbins@utk.edu or 855-6113