After a long winter it is easy to let spring fever take over when ordering plants from catalogs and buying plants from garden centers. Take the time to select plants that are suited to your garden's growing conditions and fulfill your design criteria to ensure a successful garden. Putting the right plant in the right location will result in a better-looking garden that requires less maintenance.
Most perennials are best divided in spring when they are showing a few inches of growth. When dividing a plant, save the strongest-looking parts of the plant and discard the rest. A sharp, flat garden spade works best for this job. Plants that bloom in April and May can also be divided after they bloom.
Protect emerging tulips from deer and rabbit damage by spraying with a repellent or covering with netting. Repellents need to be reapplied after rain. Netting needs to be adjusted as bulbs grow and may need to be weighted down to keep from blowing away. Animals do not typically eat daffodils, Siberian squill and ornamental onions.
Allow bulb foliage to turn brown naturally before cutting it off carefully.
Install support for perennials that require staking in early spring as they begin to grow.
Plant cool-season annuals such as pansies and primulas, which can tolerate a light frost, in early April to add color to your garden. These annuals can be used as under- plantings to bulbs to complement their flowers and carry color over until summer annuals are planted in mid-to-late May. Choose plants that are well developed with lots of flowers and buds. The cool-season annuals do not have much time to develop after planting.
Trees and shrubs
It is time to begin spraying crabapples that are susceptible to apple scab (typically this disease affects older varieties of crabs). If your tree's leaves become covered with black spots and fall off in late summer, it is in need of a protective spray program or should be replaced with a new disease-resistant cultivar. Begin spraying after the buds open and treat once every seven to ten days until the leaves are fully open (generally three treatments suffice). Call Plant Information at the Chicago Botanic Garden, (847) 835-0972, for recommended fungicides and timing for applications.
Prune out winter damage. If your evergreen shrubs, such as boxwood or yews, have brown tips from winter damage, prune them out. New spring growth will fill in where pruning was done.
Volutella blight on boxwood looks similar to winter damage with leaves turning orange to bronze and then straw-colored. The volutella fungus infects wounds in the branch bark caused by winter injury. The bark at the base of an infected branch will get loose and readily peel away from the gray-to-black discolored wood beneath. Prune out infected branches and remove any dead leaves under the plant. Spray pruners with Lysol disinfectant between plants to prevent spreading. Fungicide applications may be necessary to save plants in some situations. Call Plant Information for recommended fungicides and timing for applications.
General garden care
When turning on your irrigation system for the first time this year, monitor each zone to ensure uniform coverage. Sprinkler heads can become plugged or not rotate properly, leaving dry areas. Soft, excessively wet spots in the lawn can indicate a leak in the system.
Begin uncovering hybrid roses in early April by carefully removing mulch from the base. A bamboo stake works well for this task. Leave a small amount of mulch at the base for protection in case of a late hard freeze. Prune these roses back to live growth, which in some years may leave only one to two inches of stem.
Use an electric hand grinder to sharpen your spades. Wear ear and eye protection while doing this work. Keeping the spades sharp will make gardening much easier. New spades do not come with a sharp edge.
Continue removing garden debris from beds, being careful not to damage emerging perennials and bulbs.
Apply crab grass control if needed to lawns in early to mid-April before weeds germinate. Complete this work before lilacs begin to flower.
Install new bare-root plants as soon as you can after they arrive in the mail. Unpack plants and make sure the packing around the roots is moist. Store the plants in a cool place that will not freeze until they can be planted. It is a good idea to soak roots of trees and shrubs in water for a short period of time before planting. Do not let the roots dry out. Prune only broken branches and roots before planting. There is no need to prune to compensate for transplant shock.
Improve the health of your lawn by core-aerating. Leave the plugs on the lawn as they will break down in a short period of time. Do this before applying any pre-emergent herbicides which form a barrier at the soil surface to prevent weeds from germinating.
• Tim Johnson is director of horticulture at the Chicago Botanic Garden.