Manage winter stresses on trees and shrubs

Heavy snow and ice and frozen soil conditions can damage cherished trees and shrubs in residential landscapes. Even areas without major snowfall experience high winds and huge fluctuations in temperatures during winter. But homeowners can lessen the adverse effects of winter weather with preventive maintenance.

How to avoid damage to trees

“Branches of trees can break due to the excessive weight of ice or snow,” says Tchukki Andersen, BCMA, CTSP and staff arborist with the Tree Care Industry Association. “Tree strength can be improved with proper pruning to promote the formation and growth of the strongest possible branches and branch attachments. When pruning alone isn’t enough to strengthen a tree, properly installed cables and rigid braces can add support to weakened parts of a tree.”

Winter winds cause evergreens to lose moisture from their needles. Even some deciduous trees suffer from winter drying. If water is not available as moisture is drawn from living cells, permanent damage can result. The best prevention consists of planting only hardy species in areas of prolonged exposure, watering plants adequately in the fall and mulching to insulate the soil and roots from severe cold.

On sunny days in winter, a tree’s trunk and main limbs can warm to 15 degrees higher than the air temperature. As soon as the sun’s rays stop reaching the stem when the sun sets, the tree’s temperature plummets, potentially causing injury or permanent damage to the bark. The two common types of injury from winter sun and temperature changes are sun scald and frost cracking. The effects of sun scald and frost cracking can be reduced by sound arboricultural practices to maintain overall health, and by covering the trunks of young, susceptible trees with a suitable tree wrap.

Winter is a good time to prune

“Most skilled arborists prefer pruning when trees are dormant,” says Andersen. “With no leaves on the tree, the arborist is better able to evaluate its architecture and spot dead or diseased branches. In addition, since the ground is frozen, damage to the turf underneath the tree due to falling limbs and tree care activities is negligible. This is also a good time to check trees for diseases and other damage.”

Other recommendations to improve the health of your living landscape:

• Reduce compaction around trees to help improve water and air movement in the soil. This strengthens the tree’s root system.
• When planting, choose hardy trees available in your area as they have better chances for survival in severe weather conditions. Choosing the best location and following proper planting procedures should be your highest priorities.
• Only fertilize after a qualified tree care provider has assessed the tree’s health, growth and site conditions.
• In case of moderate storm damage, restoring the tree to its former health and beauty may take some time, but it generally can make a full recovery. Broken, hazardous limbs should be removed immediately. Pruning to remove broken stubs and restore the balance of the crown can be put off a little while, but shouldn’t be delayed more than one growing season.

For more information, visit www.tcia.org or www.treecaretips.org.