Snow itself acts as an excellent insulator if it remains for long periods. For groundcover plants, use a material that will allow air circulation and will not mat down. This prevents low-growing perennials from rotting underneath the mulch. Pine needles, wood shavings, and dry oak leaves work well for this purpose. Remember to remove mulches early in the spring to allow the soil to thaw before bud break so that the roots can once again take up water.
Snow can present problems, particularly structural damage to shrubs and trees.
Large branches with a lot of surface area are the most susceptible to breakage from heavy snow or ice. Inspect your plants for the need for preventive pruning and complete that pruning early in the winter season if possible. Otherwise, try to remove buildup of snow from branches or plants that may break under too heavy a load. If any branches should break, prune off the damaged material as soon as possible to minimize additional stress to the plant. For other pruning, it is best to wait until late February or March, but before bud break.