Evergreen shrub winter burn, sometimes called “winter scorch” affects evergreen shrubs and trees with needles (I.e.. pine trees). Winter burn occurs in harsh winters, evident by a dry, brown, scorched appearance of the leaves or needles. While all evergreens and needled trees can get winter burn, Azaleas, Hollies, and Rhododendrons are highly susceptible.
Winter burn occurs in frigid weather, and is the result of dehydrated plant tissue, as the frozen ground does not allow the plant’s root system to provide enough water to replace water lost through the leaves or needles.
All plants get energy from the sun through photosynthesis. A byproduct of photosynthesis is the release of water through the plant’s leaves. This is called “Transpiration”. Extremely cold weather freezes the ground, preventing the evergreen plant root system from drawing water from the soil to replace water lost through transpiration. The leaves die, dry out, and appear burned.
Deciduous trees, which shed their leaves each fall, are not susceptible to winter burn.
Winter sun can be a factor in drying out water-starved evergreens.
Wind also results in drying out the leaves. as a result, water is lost through the leaves.
Newly planted trees are more susceptible to winter scorch. And, if planted late in the growing season, the plant’s root system doesn’t have sufficient time to develop.
When planting evergreens, locate them away from windy areas.
Plant evergreens early in the spring, to allow the root system to get well established.
Apply a thick layer of mulch around plants, to help insulate the soil from freezing too deeply.
Select native trees and shrubs, that are naturally adapted to local winter conditions.
If the soil is dry in the winter, but not frozen, water deeply around the plant.
Use burlap bags to protect evergreens, reducing the effect of wind and sun.
Apply anti-desiccants for evergreens.