After a long Chicago winter, it is easy to let spring fever take over when ordering plants from catalogs and buying plants from garden centers. For a successful garden, take the time to select plants that are suited to your garden's growing conditions and fulfill your design criteria. Putting the right plant in the right location will result in a better-looking garden that requires less maintenance.
Improve the health of your lawn by core aerating -- removing small cores or plugs of earth to let air reach the roots of the grass plants. You can do this yourself by renting a core-aerating machine or hire a lawn service to do it. Leave the plugs on the lawn, as they will break down in a short time.
Do this before applying any pre-emergent herbicides, which form a barrier at the soil surface to prevent weeds from germinating. Since pre-emergent herbicides also will prevent grass seed from germinating, do not apply them to lawn areas where you intend to seed or overseed.
If your lawn has a deep layer of thatch, approaching an inch in depth, power-rake it to help avoid turf problems.
Thatch is a layer of intermingled undecayed plant matter -- dead and living shoots, stems and roots -- that can develop between the green foliage and the soil surface. It builds up when the turf produces organic debris faster than it can be broken down by soil organisms. Thatch can be caused by overfertilization and overwatering, especially in heavy clay soil.
Leaving grass clippings on the lawn generally does not cause thatch buildup unless you already have a thatch problem, because the clippings are so easy for soil microbes to break down.
Many shrubs have been damaged by rabbit and voles that have been feeding on the bark and shoots over the winter. The vessels that carry water and nutrients are part of the bark, so bark damage cuts off these supplies.
Stems and branches that have been stripped all the way around will most likely die above the damaged section. If the damage only goes partway around the stem, the wound may seal, and the stem may continue growing. The more bark that has been eaten, the less likely it is that the stem will live above the damage.
If you are unsure about whether or not to prune back a damaged branch, give the plant time to leaf out and see how it does going into early summer. However, cutting the damaged stems back now will likely give better results, with new growth coming from the base of the plant.
Examine boxwoods for volutella blight. The volutella fungus infects wounds in the branches' bark that were caused by winter injury. Fortunately, I have not seen much volutella blight in boxwood over the last couple of years.
The symptoms of the disease look similar to winter damage, with leaves turning orange to bronze and then straw-colored. The bark at the base of an infected branch will become loose and will readily peel off, revealing gray or black discolored wood.
Remove any dead leaves from beneath the plant, and prune out infected branches. Spray pruners with Lysol disinfectant between plants to avoid spreading the fungus on the tool.
Fungicide applications may be necessary to save plants in some situations. Call the Chicago Botanic Garden's Plant Information Service at (847) 835-0972 for recommended fungicides and timing of applications.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.