As we head into late summer, it is time to start planning for the winter to come.
If you have annuals such as geraniums and begonias that you would like to overwinter, take cuttings now. Cool nights in September will cause the stems to harden off, or grow a tough coat, which will make them more difficult to root.
Take a cutting 2 to 3 inches long from new green growth at the tip of a stem and stick it into a container of moist, well-drained potting medium, such as one part peat moss and one part perlite. Keep the cuttings in bright light. To keep them in a humid environment, cover them with a plastic bag, but ventilate it daily.
Once they are well rooted, typically in two to four weeks, transplant them to a 2- to 4-inch diameter pot filled with a sterile growing medium. Choose the pot size based on the vigor of the rooted cuttings.
Yellowjackets (a species of yellow-bodied social wasps) are unwelcome visitors to summer picnics and barbecues. They are particularly attracted to sweet things such as soda. The best way to minimize wasp problems is to practice good sanitation. Clean up spills and keep food and liquids covered.
Yellowjackets tend to make their nests in the ground or in stone walls so watch these areas for wasp activity as you are working in the garden. When the weather is warm during the day, you likely will see the yellowjackets flying in and out of the nest.
Bald faced hornets, another kind of wasp, construct large paper nests in trees and large shrubs at head height and above so watch out for them when you are working around the yard. Paper wasps, a different species, will build nests under eaves, signs and fence railings and will sting if disturbed.
Wasps are generally beneficial to the garden because they eat insect larvae and other pests that would eat plants. Control wasps only if they pose a safety hazard.
If you have a large blank space on a wall or fence, an espaliered shrub or small tree can soften it even when there is not much soil space. To train an espalier, gently bend young, supple twigs and branches to meet your design requirements. Carefully tie the branches in place with raffia or plastic tape, attaching the ties to wires or to screw eyes in the wall or fence. The ties should be secured loosely around the branches so the flow of water and nutrients through the tree's stems is not constricted. Adjust the ties during the growing season as necessary.
Formal espaliers do need regular attention to keep them looking good and likely will need to be pruned several times over the course of summer.
Do not forget to check the oil and clean out the air filter on a gas lawnmower on a regular basis. The engine can be ruined by letting it run out of oil. When you are mowing over dry leaves in the fall, the dust raised can clog up the air filter, which will impair performance of the engine.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.