Warm sun, especially from the west, and freezing nights also cause temperatures in tree trunks to fluctuate, cracking and splitting their bark. Trees standing alone in the landscape are especially susceptible to this kind of winter injury. To shield them from severe temperature swings, wrap the trunks of young, thin-barked trees with commercial tree wrap paper or burlap in midautumn. Nature provides a layer of leaves and snow around plants that stabilizes soil temperature and retains moisture. Homeowners can supplement this protection by using mulches and antidesiccants on plants.
Mulches help retain soil moisture and reduce winter injury due to water stress.
They also buffer the soil, reducing the temperature fluctuations that cause heaving. Light, porous materials are best. Leaves tend to pack, but if you chop them with a shredder or lawn mower, they make a fine mulch. Spread mulch 2 to 4 inches deep around the base of plants and trees. The foliage of broad-leaved and needle evergreens may also be injured by winter wind or sun.