How to Care for Evergreens Throughout the Winter

Every fall, there are many tasks that need to be completed before winter. Most of them involve cleanup from the summer growing season and, of course, raking the leaves. However, there are also tasks that are meant to help your plants make it through the winter looking as good at the end as they did in the beginning.

 

 

While the first concern is usually potted plants and tender perennials, there are things you should do to help your evergreens, trees and your favorite flowering shrubs survive unscathed.

Avoid Winter Burn on Your Evergreens

One of the biggest dangers to your trees and evergreens, including broadleaf evergreens like holly and rhododendrons, is winter burn. Newly planted trees and evergreens that haven’t developed a good root system are vulnerable, especially if the plant is marginal for your growing zone. 

Trees and shrubs that are planted in the open with no protection from severe winter conditions are also very vulnerable. Usually, the result of winter burn is not fatal, but it is disfiguring.

Winter burn causes the plant to lose water from the needles or leaves. Because the ground is frozen, the tree cannot take up water and resupply the plant and tissue without water will die. The severity of the damage will be determined in part by the cause and in part by the duration of the adverse conditions. 

 

 

Winter burn may not be apparent until the spring when temperatures rise and snow melts. Needles on your evergreen turn brown on the outer branches and move inward toward the trunk. Broadleaf evergreens like holly and beautiful rhododendrons will show discoloration on the outer edges of the leaves and eventually the entire leaf is affected. 

If the damage is severe, the affected needles or leaves will die and fall off. Most of the damage is usually from the south side of the plant to the west side. While most plants will survive winter burn, they won’t look as good as they did.  

What Are the Causes of Winter Burn?

There are several potential causes for winter burn. As mentioned, new transplants that didn’t have time to develop a good root system are at risk. Fluctuation in temperature can also cause winter burn. If there is a longer than normal fall with warmer temperatures than usual followed by a sudden drop of temperature to freezing, the plants don’t have time to adjust and enter dormancy as they normally would, which can put them at higher risk of winter burn. 

Strong winter winds can cause damage. Colder than normal winter temperatures or longer stretches that are colder than normal can also cause winter burn. The foliage is warmed during the day and may even start to lose water through the foliage, which is natural. But because the ground is frozen, the plant is unable to replenish the water that was lost so the plant foliage will dry out and turn brown.

Treatment for Winter Burn 

The only treatment for winter burn is to prune away the dead and discolored areas. Wait until mid-spring to prune. By then, the tree will be opening new buds and that will help you to determine where the healthy tissue starts. Sometimes, the leaves have died but the branch is still alive. If you are not sure, scratch the surface of the branch and look for green, indicating the branch is still alive and may recover. 

Use the same method on any buds. Gently open the bud looking for green. If there is no sign of life, that dead portion needs to be pruned away. The plant will eventually fill in the space that was pruned but it could take years. You will have to evaluate the plant to decide if you want to wait or if the plant should be replaced.

Prevention of Winter Burn

There are several things you can do to help prevent winter burn, including:

  • Know Your Grow Zone Choose evergreens that are hardy in your growing zone. This is probably the most important tip. Don’t start with a plant that is not meant to withstand the normal conditions of your growing zone. Chances are that the unusual weather patterns we are all dealing with will continue in the winter, giving your marginal plant very little chance of survival.
  • Wind and Sun Barrier If your area is prone to high winds throughout the winter, a wind barrier or some sort of plant protection may help to protect your evergreens

 

 

Use tall stakes and burlap or other fabric to make a wall that will block the worst of the wind as well as direct sunlight. Remove the barrier in early spring.

  • Water Before and Even During the Winter This is especially important for newly planted trees and shrubs. Established evergreens should receive one inch of water per week and newly planted evergreens up to two inches per week until the ground freezes in the fall. If your ground freezes in the winter, this is the last chance to give the plant water, so make watering a priority.
  • Mulch Keep the mulch about three to four inches away from the trunk to avoid providing shelter to mice and voles which will eat the bark from your tree. Apply two inches of mulch out to the drip line if you have clay soil and four inches on sandy soil. The mulch is applied to insulate the roots of the plant and prevent the tree from being harmed by fluctuations in the winter temperatures. Mulch helps keep the ground temperature stable. Mulch also helps to prevent the plant from heaving.
  • Anti-Desiccant An anti-desiccant will help your plant to hold the moisture inside. Spray the plant when temperatures are in the 40- to 50-degree range in fall. They are especially effective for broadleaf evergreens. There are some evergreens, like blue spruce, that should not be sprayed with anti-desiccants. Check the instructions before using. You will need to reapply during the winter months for maximum benefit and after a snowfall or rain.
  • Avoid Pruning and Fertilizing in Late Fall Both pruning and fertilizing can stimulate new growth, which will be especially vulnerable to winter burn.

By using some of these ideas, you will be able to prevent or at least minimize damage to your evergreens this winter.