Winter mulches should be applied to protect perennial plantings from winter weather. These are suggested to help protect perennial flower plantings and strawberry beds from alternating freezing and thawing cycles over the winter, not from freezing. It's best to wait awhile before mulching perennials and strawberries until about Thanksgiving or later so the plants have gone dormant and the soil freezes to apply the mulches. Straw or evergreen boughs make good winter mulches. For most perennial flowers, allowing the dead plant material to remain until spring may help protect the crown of the plant, although if the bed is mulched later this fall, it doesn't really matter.
Most ornamental grasses provide interesting winter foliage effects when left standing.
Rabbits and mice are the primary animals that may gnaw on tender bark of trees and shrubs in winter. Putting up a barrier, such as poultrywire or hardware cloth, is the best defense. Put a fence around shrubs, and secure with a few stakes. Put a loose cylinder of hardware cloth around the trunk base of younger trees susceptible to mouse or rabbit gnawing. Another problem facing evergreens during winter is desiccation, or drying out, from the wind and some cases sun.