Mulch plants that arrive too soon

The recent extended spell of warm weather and generally mild winter weather to date is resulting in some plants starting to grow in gardens. For example, some hellebores in my garden at home are showing about an inch of new growth.

There is not much to worry about at this point, nor are there any steps you can take other than lightly mulching any perennials that have begun growing to help protect them from frost damage. Any bulb foliage that has emerged and gets frosted should not affect the flowers later in spring.

• Check garden beds to be sure plants have not heaved out of the ground due to the freeze-thaw-freeze cycles that can occur in late February. Gently press the crowns of perennials back into the ground, but avoid compacting the soil by stomping heavily around plants.

Applying a layer of mulch will help prevent additional frost heaving and protect any heaved plants until later in spring when they can be properly replanted.

• Winter is a good time to prune trees and shrubs. Heavy pruning of overgrown deciduous woody shrubs can be done this month and next to rejuvenate them.

Start by removing all dead wood and prune old canes off at ground level, leaving young canes. You may need to cut back the young growth if it is spindly.

If there are not yet any young canes, cut the large canes back to about 2 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. Shrubs such as lilacs and viburnums that formed flower buds last summer will not bloom in spring if they are pruned aggressively in the previous winter.

• Arrowwood viburnum is a commonly planted shrub and a favorite of the viburnum leaf beetle. One of the most effective ways to reduce the population of beetles is to remove and destroy the twig tips that bear the eggs.

Egg-infested twig tips can easily be seen now on the twigs and it's a good time for maintenance pruning of this shrub. Once the twig tips and stems have been removed, destroy them by burning (where permitted), chipping or discarding in the trash (if the volume of debris is small).

Landscape waste pickup by villages generally begins before the eggs hatch. Destroying the egg-laying sites will reduce the insect population and in turn reduce the need to use insecticides.

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