Ask the expert
Protecting trees in winter
How can we best protect our trees from the frigid winter temps? Any tips for putting trees and shrubs to bed for the winter?
Preparing Alaskan landscape and trees for winter begins at time of planting. Trees selected for your home should match or exceed the hardiness zone for your location. Southeast Alaska should aim for trees with at least a hardiness zone of 5-6, Southcentral a hardiness of 3-4, and the Interior should aim for a hardiness zone rating of 1-2.
After accounting for hardiness zone, protecting young trees from browse damage by moose or deer may be the most important action you take for your tree. Exclusion of herbivores using a protective barrier, wire fencing, has the highest rate of success. Even retired fishing nets supported on posts have been used effectively. Trees should be protected until early spring. Fencing should be placed far enough from the tree to provide a big enough buffer for the tree to grow and to prevent a deer or moose from reaching over or through the fence to eat the tender branches inside. Hardware wire mesh may be needed around the base of trees to prevent hares and rabbits from girdling prized trees.
In addition to worrying about herbivores, young trees have thin bark and are susceptible to sunscald injury from October to early May, especially in sunny locations. When tree bark heated by the sun is abruptly exposed to cold temperatures, the living cells just inside the outer bark (phloem and cambium) can be damaged. Older trees with thicker bark are generally not affected.
Protecting trees from sunscald is relatively easy and inexpensive and involves insulating and/or shading the bark during winter and early spring for a minimum of three winters. Flexible tree wrap can be applied seasonally to protect young trees, but the wrap should be removed in spring to avoid harboring pests. Tree wraps should be light-colored, opaque, nonabsorbent and flexible. Wrapping trees may also protect trunks from rodent damage. 
An alternative to tree wrapping is to use white latex interior paint. If using paint, consider diluting the paint 1:1 with water. Do not use exterior paints, since they may contain antimicrobial agents that can damage the tree.
Dr. Casey Matney is an Agriculture/Horticulture Agent for the University of Alaska Fairbanks Cooperative Extension Service. When not at work, he can be found on the Kenai Peninsula fishing and having other outdoor adventures with this wife and four children.
