Now's the time to fertilize, plant spring-flowering bulbs
It's time to protect the trunks of young trees from deer that rub their antlers against the bark in fall. The rubbing will damage the bark and can even kill trees if the wound goes all around the trunk.
Deer typically use the trunks of newly planted and smooth-barked trees, such as young maples, that have trunk diameters of 1 to 8 inches. To protect the trunks, wrap them with tree wrap, chicken wire, hardware cloth or plastic snow fencing to a height of 6 feet. This protection can be removed in early spring.
• You may see crabgrass in your lawn now, especially if the grass has been neglected. This annual weedy grass seeds readily in the fall. Keep crabgrass closely cut to prevent seed formation or pull it out by hand. There are herbicides that can control crabgrass, but they will not be as effective after the crabgrass has set seed.
Make note of bad areas in your lawn so you can plan to apply a pre-emergent herbicide (one that prevents weed seeds from germinating) in early spring before the lilacs flower.
• Powdery mildew, a disease that causes a grayish, powdery film on leaves, is present now. This disease typically occurs in the late summer when the weather is warm and humid.
Plants that can get powdery mildew include lilacs, phlox, bee balm, zinnias and nannyberry viburnum.
Fungicides can help control powdery mildew if they are applied before the infection becomes severe, but in most cases there is no need to apply any controls for powdery mildew at this time of year. Other options include selecting more mildew-resistant varieties or moving the infected plants to an area of the garden that has better air circulation.
• Fertilize your lawn in early September to improve the color and vigor of the grass. If you only fertilize your lawn once a year, this is the best time.
Plants need more nitrogen than other nutrients, although too much nitrogen can cause excessive top growth and disease problems. In most cases, an application rate of 1 pound of nitrogen per 1,000 square feet of lawn is adequate.
Many soils in the Chicago area have adequate levels of phosphorus, so it is likely not needed for your lawn. Some villages ban the use of phosphorus to protect water quality, as surplus phosphorus can fuel algae growth in lakes and streams.
• It's time to order spring-flowering bulbs. Choose a site for bulbs that has well-drained soil. They prefer moisture in spring and fall and drought in summer. Any area in the garden that remains wet for long periods or has standing water for any length of time is unsuitable for most bulb species. Summer snowflake (Leucojum aestivum) does have some tolerance to moist conditions.
Most bulbs prefer full sun. Early bulbs can be planted beneath a high-branching tree. They will often flower before the tree leafs out, when they have only light shade to contend with.
• Divide perennials that bloomed in spring and summer as needed. It is best to do this early in the month so the plants have time to become established before winter sets in. Mulch the newly planted divisions.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.