Autumn is the time to protect the trunks of smooth-barked trees such as young maples from deer.
Deer rub their antlers on trees and typically use the trunks of smooth-barked trees. This can damage the bark and even kill trees if the damage goes all around the trunk.
Wrap trunks with hardware cloth, chicken wire or plastic snow fencing to a height of 5 feet to help protect the tree. Paper tree wrap does not provide adequate protection against deer rubs. Another option is to pound 1-square-inch wood stakes into the ground around the tree trunk to block access to the tree. Leave the protection up through the end of November.
• 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 to do it.
Nitrogen is the nutrient required the most, although too much nitrogen can cause excessive top growth and disease problems. In most cases, a rate of one pound of nitrogen per 1000 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 improve water quality as it can fuel algae growth in lakes and streams.
• Autumn also is a good time to core aerate the lawn to reduce soil compaction and thatch if you did not aerate in spring.
Core aerating once a year is enough for most residential lawns with normal use. Very high-use lawns benefit from being aerated twice a year. It also provides an opportunity for overseeding to help improve and thicken your lawn. Keep the seed moist for good germination.
Core aerating is best done when the ground is somewhat moist. Leave the soil/grass plugs on the lawn to break up and filter back down to the soil level. The plugs typically break down in one to two weeks.
Mark sprinkler heads and light fixtures in the lawn so they will not be damaged.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.