University of Illinois Extension

Preparing Your Trees for Winter

This drought ravaged summer was extremely hard on our trees, said Candice Miller, U of I horticulture educator.

“Trees have been suffering all summer long from drought stress and extreme heat. As a result, it’s particularly important this year that we prepare trees for winter by utilizing a couple of different methods,” said Miller.

Evergreens in particular should be a large concern. The problem facing evergreens is desiccation, or drying out from the wind or sun. It’s going to be most important that evergreens are well watered up until the ground freezes.

“Since evergreens do not drop their leaves like deciduous trees, they are still living and breathing throughout the winter and need to be able to uptake water as a result,” Miller said.

Shrubs in very exposed sites may benefit from additional watering and protection as well. Several options for protection include loosely wrapping with burlap, putting up a snow fence or other type of windbreak, or using commercially available anti-transpirants, which are wax-like materials sprayed on plants late in the fall to help prevent drying out. These work especially well on broadleaf evergreens which tend to suffer greatly from desiccation some years.

“Another winter problem plaguing trees is sunscald,” noted Miller. “Sunscald occurs when sunlight heats up the south and southwest side of deciduous tree trunks. This causes cells to come out of dormancy and become active. After sunset or as weather changes, temperatures may drop below freezing. This temperature drop kills active cells and conductive tissue causing injury that may appear later as sunken and discolored bark. Frost cracking can also occur as a result of this warming and freezing of the trunk.”

Sunscald can be managed by using commercial tree wraps which are made of crepe paper and help to insulate the bark. In late October or early November, wrap trunks upward from the base of the tree to a point just above the lowest branches. This is typically done on younger trees until they are able to develop thicker bark to serve as protection. These trunk guards should be of a light color so that they can reflect sunlight during winter thereby reducing the temperature on the bark. Be sure to remove tree wrap and tape the following April to avoid girdling and possible insect damage.

“Winter feeding of rabbits and voles may also be of concern,” she noted. “Putting up a barrier, such as chicken wire or hardware cloth, is really the easiest and best defense for trees. Put a fence around shrubs and put a loose cylinder of hardware cloth around the trunk base of younger trees susceptible to vole or rabbit gnawing. Removing excess vegetation and debris near plants will also help reduce cover, especially for voles.

“Preparing your trees for winter may be a small additional amount of work, but the payoff of having a healthy tree next spring is definitely worth it.”