Winter burn happens when plants dry out during the winter. Even during the colder months, evergreens continue to lose water vapor through their needles, which are modified leaves. The plant attempts to replace the water by pulling it from the roots. However, when the ground is frozen, the roots cannot absorb enough water to supply it to the dry needles. If the weather turns breezy, warm and sunny while the ground is still frozen (like today, in the Midwest), evaporation from the needles increases and water cannot be replaced fast enough. Discolored, brown or burnt-looking foliage may start to appear when this happens. In fact, winter burn indicators typically develop during warm weather in late winter and early spring.
Winter damage is often misdiagnosed as a disease or as damage from excessively cold temperatures. The damage which starts at the tips, is brown or rust-colored and generally on the side of the plant facing the sun and/or the side exposed to the wind, where the rate of evaporation from the needles or leaves is greatest.
Winter burn can be more prevalent in years in which the ground freezes early before plants are acclimated to cold weather or when there is little snow. Without snow cover or mulch to insulate the soil, the ground can freeze more deeply. Although this is not always true, as the amount of snow did not matter this year because of the frigid temperatures, the ground is still frozen about 2 feet down.
Light pruning can remove the burn, however some lazy gardeners (ahem… the author) wait for the needles to completely dry and brush them loose / let them fall a bit later in the season.
Winter Burn Management Strategies
Water well in fall: One inch per week or saturate to the depth of 12” to 18” inches. Watering should be continued through late autumn into early winter as long as the ground is not frozen.
Mulch: Use mulch around the plant so the entire root zone is covered. This will reduce moisture loss.
Build a barrier to wind. A burlap barrier can deflect wind from the plant.
Promote good culture. Monitor the amount of moisture in the spring when the plant is coming out of a period of frozen ground, and low moisture availability. Water as needed if the rainfall is less than an inch per week.
Many broad-leave evergreens such as: holly, boxwood, yews and rhododendrons will also have some winter burn this year.
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