I have finally been able to spend some daylight scouting my home landscape for cold damage. Robeson County is rated Zone 8 for cold hardiness with a minimum temperature of 10-15 degrees. I know this is unofficial, but the temperature dropped to 10 degrees and 7 degrees two separate mornings at my home during our last arctic blast. I did find minor damage on many trees and shrubs. Revealing native plants’ advantage in your landscape – three red maples transplanted from our surrounding farm showed no damage, but a red maple cultivar I purchased years ago (on the basis of its predictable columnar shape and fall foliage) did show cold damage, even though it originated from a native plant. Another interesting observation I found was between the two “Natchez” crepe myrtles in my yard; one showed no damage, but the one Hurricane Matthew flooded and kept submerged for several days did show some cold damage. A healthy, vigorous plant is better able to sustain itself. Limb and twig die-back can be removed with proper pruning before bud break in the spring.
The poor “Knock Out” rose appears to have fared the worst; its foliage is totally desiccated, but that can be remedied before spring. Prune your roses back to healthy canes, leaving around two feet of canes late winter. Leaf scorch symptoms appear just as it sounds, resulting from cold damage, and is most prevalent on broad-leaved evergreens. Damage is most severe on shallow-rooted plants, such as azalea, rhododendron, holly, and boxwood. Keep the soil moist, but not wet, with three to four inches of mulch placed over the root zone. The use of mulches conserves soil moisture, prevents temperature fluctuations, and keeps the soil cooler in early spring, which aids to reduce premature bud break.
In fruit crops, I saw little damage on my pear tree, but the peach trees did show bud and twig damage. The grapevines looked good, except for a new cultivar I am trying which showed some damage, but that can easily be removed with proper pruning in February. This particular cultivar has been in the ground less than a year; its lack of establishment can definitely contribute to its weaker ability to withstand the cold.
Many of you will have cold damage in your lawns and landscapes. The signs of cold damage can be confusing, since some damage may not be evident until months later. Some leaves and tender shoots subjected to freezing temperatures or cold damage can appear water-soaked and wilted. These tissues will usually turn black within a few hours or days. The tips of narrow-leaved evergreens, such as junipers, may turn uniformly brown. Broad-leaved evergreens, such as hollies, often have marginal leaf burn. Most damage can be removed by pruning before spring. The plant can benefit from your decision to prune as late as possible, but before bud break. Pruning early in the winter removes energy reserves the plant needs to survive the dormant period.
For more information, please contact Mack Johnson, Extension Horticultural Agent with North Carolina Cooperative Extension, Robeson County Center, at 671-3276, by E-mail at Mack_Johnson@ncsu.edu, or visit our website at http://robeson.ces.ncsu.edu/.
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