When you enjoy gardening, you'll love autumn
Fall is a great time to plant and transplant trees and shrubs. Fall conditions, which include warm soil, moderate air temperatures and rain, help plants re-establish their root systems.
In general, trees and shrubs do not need to be pruned when transplanted to compensate for loss of roots during transplanting.
Evergreens benefit from planting early in the fall to minimize chances of winter burn. Try to get them planted before the middle of October and continue watering them weekly or as needed until the ground is frozen. They should not go into winter under stress from being too dry.
Mulch is also important to install for fall plantings. Use 2 to 3 inches of mulch for trees and shrubs and 1 to 2 inches for perennials and ground covers. It is best to keep the mulch away from the crown (base) of the plants.
• Good soil preparation is important for a successful planting. It is best to amend the entire planting area or bed instead of individual holes. Evenly incorporate 2 to 3 inches of compost into the existing garden soil.
• Peonies are dependable, long-living, hardy perennials. Their neat foliage stays green from spring until frost, and follows large, showy blooms.
September is a good time to plant peonies, as well as divide and transplant existing ones. They do best in full sun, although they can tolerate partial shade. Flowering is reduced if placed in the shade.
When dividing, lift roots carefully and use a sharp tool to cut the large, fleshy roots into smaller pieces. Be careful not to make these pieces too small — each section should have at least three eyes. The eyes are reddish growing buds that emerge from the top of the roots. You will find them in spring and fall. Set these divisions an inch or two below ground.
• It is time to start thinking about the indoor herb garden. Before frost, carefully lift and pot small herb plants or large perennials such as rosemary or lemon verbena to bring inside.
After lifting them from the ground, you may want to keep them outside for a few days in a partially shaded spot with even moisture. This will help them adjust to a move indoors. The shock from moving plants from outside to inside can cause some yellowing of leaves.
Once inside, keep the herbs in a sunny window.
• Be aware of the weather as you spray to control weeds in the fall. Herbicides are most effective when temperatures are consistently above 55 degrees and weeds are actively growing. Spot spray the weeds to minimize the amount of herbicide you use.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.