How you can improve the health of your lawn with core aeration

If you’re looking to improve the health of your lawn this year, I recommend core aerating — a much better annual maintenance practice than power raking, in my opinion.

You’ll want to leave the plugs on the lawn; they’ll break down in a short period of time.

Do this before you apply any preemergent herbicides, which form a barrier at the soil surface to stop weeds from germinating. Crabgrass is a common target plant to control with this type of herbicide, so there’s no need to use one if crabgrass hasn’t been a problem for you. Preemergent herbicides will also prevent grass seed from germinating, so be sure you coordinate any seeding with use of a preemergent herbicide.

Lately I’ve been seeing many shrubs that were damaged by rabbit feeding during the winter. If rabbits eat all the bark off stems and branches, the shrub will most likely die above the damaged section since food and water won’t be able to move between the roots and foliage of the plant. If the damage only goes partially around the stem, it might heal and continue growing; the more bark that’s been eaten from the stem, the more likely the stem will die above the damaged portion.

If you’re not sure about whether to prune it back, you can give the plant time to leaf out and see how it does with consistent warm weather in early summer. Cutting the plant back now, though, will likely give better results for new growth coming from the base of the plant.

Winter damage to evergreens is getting more visible in gardens, in addition to damage with the recent warm weather. Your plants will probably recover fine if the damage is only on the exterior foliage and there’s healthy green foliage deeper in the plant, but they may still be in trouble if the remaining foliage is starting to dry out even though it’s green.

Scratch the bark on a few stems to see if there’s any green color under the bark. Any branches that are off-color and have bark peeling off the lower stems most likely won’t make it.

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