Take cuttings from annuals for next year's garden

It is time to take cuttings of annuals, such as geraniums and begonias, that are to be kept over the winter. Cool nights in September will harden off the plants, which will make them more difficult to root.

Take a tip cutting 2 to 3 inches long and stick it in a well-drained potting medium such as one part peat moss and one part pearlite. Keep the cuttings in humidity and bright light. Cover the cuttings with a plastic bag and ventilate daily by opening and resealing the bag.

Once they are well-rooted, typically in two to four weeks, transplant them to a 2- to 4-inch pot filled with a growing medium. The size of the new pot will depend on the vigor of the rooted cuttings. Keep the plants in a brightly lit window.

• Populations of yellow jackets (a yellow-bodied social wasp) build up in late summer. They are unwelcome visitors to picnics and are particularly attracted to sweet things like soda. Keeping your patios and decks clean is the best way to minimize problems with yellow jackets, as well as other pests.

Yellow jackets tend to make their nests in the ground or in stone walls, so watch these areas as you are working in the garden. When the weather is warm during the day, there will be a lot of activity with the yellow jackets flying in and out of the nest.

Baldfaced hornets construct large paper nests in trees and large shrubs at head height and above so you should be aware as you are working in the garden. Paper wasps will build nests under eaves, signs and fence railings and will sting if disturbed.

These are beneficial insects so control them only if they pose a safety hazard.

• Do not forget to check the oil and clean out the air filter on your lawn mower on a regular basis. It is easy to overlook these basic maintenance tasks as you mow throughout the summer.

The engine can be ruined by letting it run out of oil. It is a good idea to sharpen your mower blades after about every eight hours of use.

• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.