Winter Burn On Evergreens

Minnesota’s winters can be really tough on landscape plants. The combination of cold temperatures, winter sun, and drying winds can damage or even kill buds, bark, roots. Hungry mice and rabbits can nibble away at bark and branches, causing severe damage or even death. In addition, evergreens, can suffer from winter burn, the most susceptible being juniper, pine, hemlock, arborvitae, and yew. New plantings can get hit especially hard.

Evergreens are usually one of the earlier plants to show visible signs of winter injury in the spring, known as winter burn. This happens when the ground is frozen, and the winter sun and wind causes the leaves to lose moisture. Because the plant can’t replace the lost moisture from frozen soil, they literally dry out and turn brown. This normally occurs on the south or southwest side of the plant, or if it is in an exposed location, on the windward side. A very important contributing factor is lack of snow cover, especially when the soil freezes early before the needles get a chance to acclimate to the cold weather ahead, causing even more moisture loss. A late cold snap in the spring after the branches have leafed out can also cause browning.

This doesn’t necessarily mean the death of the plant, however, so don’t get impatient and cut out the brown branches. In many cases, the branch itself will still be alive and will send out new shoots. (See photo at right) However if you can’t stand looking at the brown needles, try getting out your old kitchen broom and brush them off of the plant. Just be sure you don’t break any branches. Photo at right is from R. W. Stack, North Dakota State University. Click to enlarge.

Prevention

The best way to prevent winter burn on your evergreens is to plant them in the right location. Avoid locations that are both exposed to the northwest winter wind and the winter sun . Also keep them away from your furnace or clothes dryer vent! Some evergreens are more tolerant of winter burn than others. Teuton yew and Techny arborvitae are two that can be safely exposed to the winter sun.
Also, make sure your evergreens don’t go in to the winter with the soil dry. The plants need moisture in the soil to replace the moisture loss from the leaves. Make sure you keep them well watered, especially if they have gone through a dry spell in the late summer or fall. October and November (and sometimes December) is not too late, as long as the soil is not frozen and will take the water.
If you have already planted them the situation described, or that plant “just has” to to be in that location, then some winter protection may need to be provided in the way of protection from the winter wind and sun. The most common way is to use a sheet of burlap (available at most large garden centers) wrapped around the plant and held together by twine. Just make sure you don’t wrap it too tight, and leave it open at the top for air to get in and out.
Anti desiccants have also been used. They are mixed with water and sprayed on the plant, leaving a “waxy” coating to prevent moisture loss. However, recent research has shown the results to be generally disappointing.