Spring has sprung and Mother Nature is returning color back into our landscape; trees are breaking dormancy, spring ephemerals are covering the forest floors and flower blooms are becoming abundant. This flush of growth brings relief that winter is behind us, but also accentuates the damaging effects of the past dormant season.
Specific winter injury that is annually observed in our area is called “winter burn.” Plants susceptible to winter burn include broadleaved evergreens (boxwood, azalea, rhododendron, etc.) as well as needled evergreens (spruce, fir, yew, arborvitae, hemlock, etc.) Foliage does not actually burn but rather dry up. During the winter season we think of plants being “at rest” when actually evergreens continue to lose water through photosynthetic processes, although at a much slower rate than during the growing season. Winter burn occurs when the amount of water lost from the leaf tissues exceeds the amount of water roots and stems are able to transport. When the soil becomes dry or frozen, the roots are unable to take up and replace the water lost during this process. Extremely mild and extremely cold winters commonly result in winter burn and in both cases is exacerbated by lack of snow or rain. Strong winds and abundant sunshine can also further the damage.
Damage associated with winter burn is browning, yellowing, or scorching of leaf tips or needles. Typically damage is noted late-winter and accelerates in early spring. Foliar damage often favors the south, southwest or windward sides of evergreens, but in severe cases the whole plant may be affected.
If you have noticed plant material on your property experiencing this sort of damage, keep in mind, steps can be taken to help reduce occurrences in winters to come. In the fall, properly water evergreens during dry periods, up until the ground freezes. Establishing mulched tree rings around sensitive plant material will help to insulate the soil and conserve soil moisture. Unprotected sites vulnerable to winds may benefit having a barrier constructed to break this force reducing the impact and risk of dehydration thereby minimizing overall winter damage. Install a barrier made of burlap or similar material, on the windward or vulnerable sides of the evergreen. If plant material requires fencing to all sides, be sure to leave the top open to allow for air and light penetration.