Brown, burned out evergreen branches are a common site in the spring following a harsh, Midwest winter. Burning occurs in all types of evergreen trees and shrubs, such as needled evergreens (spruce, fir, pine, hemlock, and yew), broadleaf evergreens (holly, rhododendron, azalea, euonymus, and boxwood), and scaled evergreens (arborvitae, juniper, and false cypress).
In addition to lending an unsightly appearance, winter burn can pose a serious threat to the integrity and vigor of the entire plant. The more severe the winter conditions, the worse the ensuing burn. Fortunately, there are steps that can be taken to mitigate the harm to your beautiful evergreen landscape!
Winter burn on a yew shrub
1. Identify the Problem
Winter burn is typically noticed in late winter and early spring as temperatures rise. The tips of branches begin to turn brown and the brown color progresses deeper in toward the center of the plant. On broadleaf evergreens, the browning occurs on the margin of each leaf and may gradually encompass the entire leaf blade. The sides of the plant which face south, southwest, or west often experience the most damage.
Burned boxwood shrubs
2. Understand the Cause of the Problem
The first step to eliminating winter burn is to understand the environmental conditions which cause the burn. Rapid water loss through leaves and needles and inadequate re-uptake of moisture through the roots is the main culprit.
Trees and shrubs exposed to direct sunlight and wind transpire more water than trees and shrubs in sheltered locations. When the ground is frozen during winter, a plant cannot uptake adequate moisture through its roots to replace the water lost through the leaves or needles. This in turn causes the plant to dry out and burn.
Evergreens planted close to roads, driveways, and walkways are particularly susceptible to burning. These plants are exposed to excessive levels of salt and ice-melting chemicals, both of which cause plants to dry out and require more moisture. Choose salt-tolerant plants when planting near driveways or sidewalks.
Winter burn can also occur as a result of long winters or winters with unusually cold temperatures. Very cold temperatures late in the Spring may also be a factor.
Winter burn on hemlock and arborvitae
3. The Solution
Plants grown and produced locally are more well-adapted to seasonal weather conditions. When possible, purchase plants from local nurseries. Delicate evergreens (such as boxwood, rhododendron, and azalea) should be planted in sheltered areas away from direct sunlight and wind.
Avoid pruning or fertilizing your evergreens in late summer or early fall. Pruning or fertilizing stimulates new growth. New branch tips and foliage require plenty of time to mature and harden off in order to be ready for the cold months.
Add a few inches of mulch around the bases of your evergreens in the fall to insulate the roots. If there is inadequate rainfall, evergreens need regular supplemental watering through the fall right up until the ground freezes.
Building a temporary barrier around evergreens with stakes and burlap or landscape fabric will offer protection from the sun and help deflect icy wind damage.
Apply an anti-dessicant, such as Bonide’s Wilt Stop, to help preserve evergreens through the cold. This waxy spray covers the needles or leaves and prevents the plant from transpiring and drying out. This spray may need repeat applications following heavy rain or snowfall.
Wilt Stop, an anti-desiccant spray