Woody shrubs can be heavily pruned this month

Winter is a great time to prune trees and shrubs — it’s by far my favorite gardening task and plays a key role in maintaining a great looking garden.

Overgrown deciduous woody shrubs can be heavily pruned this month and up until new growth begins in spring to rejuvenate them. Start by removing all the dead wood.

For old canes, prune them at ground level whenever possible, leaving the younger, thinner canes intact. A small folding handsaw is particularly handy for this task. Many gardeners hesitate to prune aggressively enough to properly rejuvenate overgrown shrubs, but it’s often necessary. If the young growth is weak or spindly, you may need to cut it back as well.

Keep in mind that shrubs like viburnums and lilacs, which formed their flower buds last year, won’t bloom this year if you prune them now, as most or all of the flower buds will be removed.

If there are not any young canes, cut the large stems back to two to three 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. Check these plants later in spring and cut out any dead sections in the stems. Then continue to prune out the old stems in subsequent winters until they are completely removed and replaced with healthy new stems.

Don’t forget to water any evergreens planted in containers outside during warm spells this winter. Evergreens continue to lose water through their leaves and will be more likely to suffer winter burn if they dry out in the containers.

It is best to keep any logs that you saved for burning in the fireplace outside until you are ready to burn them as insects can come in with the firewood. Never treat firewood with insecticides.

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