Overgrown shrubs can be cut back in winter

Winter is a good time to prune trees and shrubs. Overgrown deciduous woody shrubs can be heavily pruned to rejuvenate them this month and until new growth begins in spring.

Start by removing all dead wood. Prune old canes off at ground level whenever possible, leaving young canes that are smaller in diameter. You may need to cut back the young growth if it is spindly.

If there are not any young canes at the base of the shrub or lower on the large stems, cut the large stems back to 2 to 3 feet from the ground. This will be unsightly, but if the plants are healthy, extensive new growth should start from the old canes in spring and fill in the plant.

I generally wait until mid- to late March when a shrub needs this treatment to reduce the amount of time it looks bad.

Shrubs such as lilacs that formed flower buds last summer will not bloom if they are pruned aggressively in winter.

• Don't forget to water any evergreens planted in containers outside during warm spells this winter. So far, the rain during the warm spells has probably kept your plants in good shape. Evergreens continue to lose water through their leaves and will be more likely to suffer winter burn if they dry out in the containers.

• If tree branches become covered with ice, let the ice melt naturally rather than cracking it with a heavy object.

If large evergreen branches are anchored to the ground with snow, gently sweep off snow with a soft broom and then elevate the tree branch from underneath. Using heavy objects like shovels risks damaging the tree bark.

Evergreens that are bent over may be able to be straightened when temperatures warm and the snow and ice melt.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.