Spring pruning tips: When and how to shape your garden shrubs

Pruning is my favorite gardening task and I am happy that the pruning season is quickly approaching. It’s a good time to prune back shrubs that bloomed early in spring. However, I’d avoid pruning summer-flowering shrubs like hydrangeas. Lightly prune back any unshapely growth on your early-blooming shrubs to improve their appearance and encourage the development of a fuller plant. Some of your shrubs may need more time to leaf out before you decide to do more drastic pruning of dead wood or remove them. Go ahead and prune out any branches that you know are dead.

Practice integrated pest management in your garden to reduce the need to use pesticides. Begin by choosing the proper plant for your site and using good planting practices such as amending the soil with compost and planting at the proper depth. When possible, select plants that are resistant to common diseases and give them the appropriate care to minimize problems. Monitor all plants carefully for insects and diseases. If trouble arises, identify the problem and use the least toxic control measure when damage is not tolerable. Timing is also important. Apply controls when pests and disease are most susceptible. Never spray just because you see insects, as some of them might be beneficial or harmless. When you use an insecticide, you kill the good insects along with the bad ones. Look for more pest- and disease-resistant varieties to replace any plants that have had a pattern of problems in your garden.

Weeds are really growing now. My definition of a weed is a plant that is out of place. A good time to weed is when the soil is moist, so the roots come out more easily. It’s very important to get weeds out before they go to seed. A small hand weeder or trowel is helpful. Look for tree seedlings such as buckthorn, mulberry and box elder that tend to establish themselves in hedges and in the base of shrubs. If you look closely, they are easy to spot.

We have an infestation of Star of Bethlehem at home. It is an invasive, bulb-forming perennial weed with white, star-shaped flowers that aggressively spreads in the lawn and in beds and is toxic to humans and animals. Our dogs pay them no attention, so we haven’t had to worry. It’s very important to use a trowel or weeder to remove the bulbs and discard them in the trash or send them to a commercial composting operation where they will not continue to spread.

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