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How to prepare your trees for winter

November 7, 2020
small tree in snow with tree guard around the trunk

Trees can experience many stresses during the winter months including lack of water, sunscald, wildlife damage and winter injury. Young trees (one to five years old) should be watered throughout the year, until the soil freezes. Watering young conifer trees from October to soil freeze-up is critical. 

Sunscald

Sunscald is caused when the sun heats up the bark during a cold winter day. Then clouds, trees or buildings will block the sun causing rapid freezing of the bark tissue which results in the cracking of the bark. Trees with thin bark are often affected by sunscald, including cherry, crabapple, locust, linden, maple, mountain ash and plum.  To protect from sunscald, young trees should be protected with white plastic tree guards or white tree wrap. 

Wildlife

Many mammals can damage trees in winter including mice, voles, rabbits and deer. If wildlife removes the bark completely around the tree and girdles the trunk or stem, it will kill the tree above that damaged site. 

  • Remove excess grass and vegetation from beneath and around all shrubs and trees. 
  • Install white plastic tree guards, tubes, or wire fencing to protect the bark and trunks of trees.
  • If you have voles, make sure the guards and fencing are below the ground at least two to three inches.

Note: During heavy snow and wind periods, check snowdrifts near protected trees. If the drifts are taller than the tree tubes, rabbits may walk on the drift and chew your trees.

If deer are in your area and you have young white pine or white cedar trees, protect them by bud capping. Bud capping involves stapling a piece of paper on the leader or terminal bud. Fencing around trees at least eight feet tall can also be effective. Young deciduous trees should be protected from rubbing on the trees from bucks. A number of spray repellents can repel deer because their taste or odor may turn deer away. Repellents will likely need to be re-applied consistently. 

Drying out

Conifer needles tend to dry out in cold windy weather during winter months. No water is being transferred to needles and they dry out turning brown in the spring this is called winter injury. The best approach to keep conifer trees healthy is to water them from October till the soil freezes. 

Burlap barriers on the south side of conifers can minimize drying out. Burlap wraps can be used to cover arborvitaes that are prone to winter injury, leaving the top open. Yews, hemlocks and arborvitaes can be planted on the north and northeast sides to protect them from wind and winter sun. Brown needles on the lower branches of spruce trees may be a sign of a needle cast disease.  

More online resources for protecting trees through the winter include the following:

Gary Wyatt is an Extension educator with a focus on agroforestry and bio-energy based at the Mankato Regional Office.

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