Protecting plants once the temperatures begin to drop in late fall allows them to overwinter healthily. Winterizing perennial plants, trees and shrub protects tender new buds and prevents ground heave. Ground heave happens as the ground goes through periods of freezing and thawing throughout winter. This process may damage roots or even uproot a plant entirely. Another concern is disease. Plants not properly prepared for winter are more likely to become victims of disease that could have been avoided.
Stop pruning and fertilizing trees and shrubs in late summer or early fall. This encourages plants to begin entering dormancy and prevents fresh cuts from being exposed to freezing temperatures.
Cut back perennial flowers, such as peonies, once the foliage begins to die off or after the first hard frost in autumn. Cut the plants down to approximately 5 inches above the ground using clean, sharp shears.
Rake up and remove all sheared off plant material, dead leaves and fallen pine needles. Remove from the bed and compost if there are no signs of disease, otherwise throw them away.
Water each plant thoroughly right before the first expected hard freeze in your area. This prevents winter dehydration, which makes plants more prone to disease.
Apply a 3-inch layer of winter mulch around trees and shrubs, but don't place the mulch right up against the trunks of the plants. Cover perennial beds with a 3-inch layer of straw mulch or pine boughs to maintain soil temperature and protect against winter heave.
Cover tender plants with a breathable cover, available at garden stores. This prevents winter burn, which may kill the plants otherwise.
Prune off any winter-damaged or dead branches from trees and shrubs in early spring before the plants begin actively growing again. This prevents disease that set in over winter from spreading to healthy parts of the plants, and it prevents disease from entering the plants once they begin actively growing again.