Sheltering outdoor plants from severe winter weather can prevent a wealth of problems, ranging from broken branches and damaged roots to increased vulnerability to disease. Use simple materials--some of them already in your yard--to strengthen plants to endure the rigors of winter.
Protect branches from winter wind, ice and snow damage by pruning straggling, leggy and weak branches back to a growth junction as plants enter dormancy in the fall. This will prevent breakage, tearing and splitting that can damage larger portions of plants. If pruning branches larger than 1 inch in diameter, protect cut surfaces with grafting wax or wound paint to prevent disease and ice damage. Prune back dead foliage and stems on flowering perennials to prevent wind damage that can pull on roots.
Protect base stems and roots from freezing temperatures, ice and snow. Mound top soil, wood chips or shredded bark mulch around plant roots and lower stems, to a height of 3 to 6 inches. Rose growers routinely mulch over hybrid graft sites low on main stems; that way, a rose that was pink last summer will remain pink in seasons to come.
Use burlap or permeable landscape cloth and green stakes to build wind-barriers around vulnerable hedges or free-standing evergreens. Water and warmth will penetrate the cloth, but wind-damage will be less.
Make a greenhouse with plastic sheeting and green stakes around perennials and small evergreens in planters. Place movable planters in clear plastic bags. Anchor a green stake in the soil and gather bag edges around it. Cut some holes or slits close to the rim of the planter to allow for moisture from rain and snow to enter. Wrap sheeting and stake it around large planters that cannot be bagged. Translucent plastic permits light and warmth to penetrate.
Augment cold protection inside weather barriers by adding 6 inches of shredded bark mulch or fallen leaves. Some gardeners substitute shredded newspaper.
Use the branches from your post-holiday Christmas tree and other evergreen decorations to protect plants during mid-winter ice storms. Build tents over roses and other vulnerable perennials with branches. These temporary shelters prevent heavy snow and ice from breaking plants. (Cut and store the trunk of your Christmas tree to fuel next year's Christmas fireplace.)