Caring for Trees in the Winter: Cold Stress

Winter weather can take a toll on trees all throughout the northern states of North America. For species that are native to the colder regions, this can still be a stressful time. The weather can be particularly stressful for the more isolated and expose trees in the residential landscape. Some of the stress the trees face is completely unavoidable. We cannot control the climate we face. There are some things we can do to minimize the damage caused by cold stress, though.


Cold stress can be seen in many ways. On mature trees, the main effect comes from the change between the heat in the daytime the freezing at night time. The variation in temperatures causes stress within the tree between the inner wood in the outer bark that leads to cracks. This is called southwest injury or frost cracking. There is usually little that can be done to prevent this problem. In most cases, the tree repairs itself. The area that is cracked remains vulnerable and any future cracking it happens at the same place is more likely to cause major damage. With younger trees and those considered tropical, the owner should wrap the bark of the tree in the fall. There are cold weather tree blankets available specifically for this purpose.


Another issue with cold stress is when there is an early frost on growth that is late. When a tree has late growth, it is vulnerable because it has not had time to prepare for the cold. The cell walls can be ruptured by ice crystals that are growing on the new tips of the branches, causing them to die in the next season. To keep this from happening, you should wait to prune after the tree has become dormant in the fall. If you pruning too soon, new growth will be encouraged and will increase the risk of damage from frost. Also, never use the fertilizers that come with the quick release nitrogen in high amounts. With proper fertilization in the fall, your trees will be benefited, but it is important to know what you should and should not use on them.


Hopefully these tips will help you your trees healthy during the cold of winter. Cold stress can be a huge issue with trees, but by taking preventative measures, you can protect your trees.

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