Buckthorn is an invasive tree and common weed in Chicago area gardens. It tends to hold green leaves later than other deciduous trees and shrubs in fall so it is easy to spot later in the season.
Cut buckthorn at ground level and quickly treat the stump with an herbicide to kill the root system. Smaller trees can be dug out with a sharp spade.
• Shredded leaves make good mulch for your garden beds. For the serious gardener, a shredder can be rented, but be forewarned that they are very noisy, so it is best to use ear and eye protection when shredding leaves. Using a shredder is a time-consuming process but results in finer leaf mulch.
For the average gardener, a lawn mower with a bag to catch the leaves is adequate for this job. The mower doesn't cut the leaves up as finely as a shredder but works a lot faster. Ground-up leaves will also decompose more quickly if you are using them in a compost pile.
Shredded leaf mulch can also be purchased from garden centers.
• In general, it is not necessary to mulch established perennial borders. Leave perennials up for winter interest and leave a light layer of leaves in the bed to provide some winter protection. Cut back perennials when they start looking bad.
Any new perennials planted this year -- especially those installed in late summer or fall -- should be mulched for the winter. The freeze-and-thaw cycles in spring can push newly planted perennials out of the ground.
• It is a good idea to disconnect garden hoses from outdoor spigots and faucets as night temperatures begin to drop. If you leave a garden hose attached, a small amount of water can stay lodged in the pipe near the spigot and quickly freeze. This ice can damage your faucet and pipe.
Reconnect hoses to water new plants or plants in containers as needed during any warm spells.
Once you have finished watering for the season, turn off the water supply inside your house, disconnect hoses and tighten all the faucets after opening them to drain out any remaining water. It is important to keep water out of exterior pipe systems that will not be used in the winter because trapped water can freeze and expand, causing cracks and breaks and even bursting pipes.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.