Winter injury occurs for several reasons and there are steps we can take to minimize risk of occurrence.

Frost injury occurs usually in fall and early spring when tender tissue is not hardened off for cold. Water in cells freeze, expand, and burst, causing tissue death. Covering plants to hold in ground heat can often keep temperatures around the plant warm enough to keep frost damage at bay. Plants do not generate heat the way animals do, so wrapping the top of the plant and cinching it closed below will do little to protect it.

Winter desiccation occurs when a plant loses more moisture than it can take up from frozen soil. Leaves turn brown, first at margins, and then the entire leaf. Plants exposed to wind are more severely affected as are plants that are not properly hydrated. Be sure to water and mulch before extreme cold of winter sets in.

Woody die back (low temperature injury) occurs when a plant is planted outside of it’s hardiness range, when temperatures drop below normal for an area, or when temperatures drop suddenly and plants are not properly hardened off for cold. This results in dead branches or delayed and stunted regrowth in spring. Avoid planting outside of the recommended hardiness zone. In eastern North Carolina, do not fertilize after August 15th to avoid tender, new growth as winter approaches.

Sun scald and bark splitting both occur because of rapid day/night temperature fluctuations. Sun scald results from a cold night after a very warm day (occurring on the West and Southwest side of trunk) while frost cracking results from rapid temperature rises after a very cold night (occurring on the East and South east sides of trunk). These usually occur on thin-barked plants. Wrapping trunks in fall reduces risk of either, especially if they have occurred on a plant in past years.