Trees need care in winter too

Winter is almost upon us. It’s my favorite time of year. Everything slows down: more time with family, the holidays and long walks in the snow…. But winter also brings bitter cold winds, blizzards and heavy wet snow. If you think this is hard on you, think how difficult it must be for your trees. After all, they can’t just get up and throw on a warm jacket. Trees need a little help to get through the winter with minimal damage and stress.

Trees go into a state of dormancy during winter, but they are not completely inactive. Trees can take up water if the soil is not frozen. They can also lose water due to evaporation from cold drying winds. Evergreen trees are particularly susceptible because the foliage remains green and active through the season. This green foliage loses water readily, and the leaves can desiccate leaving them dry, brown and unsightly. Help your trees, evergreen or not, to weather winter gracefully by following these tips from the International Society of Arboriculture (ISA):

  1. Place a thin layer of organic mulch around and within the drip line of your trees. Two to three inches of aged wood chips or shredded bark insulates tree roots from the cold and holds in precious soil moisture. Keep mulch at least two inches away from the trunk to prevent root rot or damage from rodents.
  2. Provide water. Yes, you do need to water your trees in winter, especially in areas without persistent snow cover. A layer of snow provides a slowly released source of moisture to tree roots. Where snow doesn’t last, be prepared to get out about once per month to moisten the soil around tree roots. This is particularly important when we experience a winter “thaw” and temperatures rise temporarily. Take advantage of these times, when tree roots can actively absorb soil moisture, by giving them a long drink. Apply water out to the tree drip line, and make sure the water soaks at least 18 inches into the soil.
  3. Prune out old and damaged wood. Winter is a great time to prune deciduous trees (the ones that lose their leaves) because the branch structure is so easy to see when the leaves are gone. Prune out dead wood and crossing branches for healthy, vigorous trees come spring. Make all pruning cuts down to the point of attachment to a larger branch. Don’t leave “stubs” that can decay and become entry points for disease and insect pests.
  4. Minimize structural damage to young trees by wrapping the trunks with a rigid plastic or wire guard. Cardboard wrapped loosely around the trunk works just as well. Plastic and cardboard protect the trunk from winter temperature extremes and prevent frost splitting. These guards also protect tender young tissues from damage by deer or rabbits. Don’t forget to remove the guards in spring so trees aren’t damaged when they resume growth. Damage can also occur on both young and mature trees due to the weight of heavy snow or ice. This is when early pruning for good tree structure can really pay off. Weight on poorly placed branches can cause branch cracking and breaking. Branches that break under stress may tear away the bark beneath the break, leaving tender tissues below the bark open and exposed. Trees with V-shaped crotches or narrow branch angles are particularly vulnerable to structural damage.  If you have concerns about your tree structure, or you need pruning advice, call a certified arborist. For a list of certified arborists in your area, visit www.isa-arbor.org.