Time to plant your trees and shrubs

Fall is a great time to plant and transplant trees and shrubs. The warm soil, moderate air temperatures and rain of autumn help plants re-establish their root systems after transplanting.

Although deciduous trees and shrubs can be planted later, evergreens benefit from planting early in the fall. This will allow them to develop enough roots to pull up water into the branches and needles before winter, minimizing the chances of winter burn.

Try to get evergreens planted before the middle of October. Water them weekly or as needed until the ground is frozen. They should not go into winter under stress from being too dry.

In general, trees and shrubs do not need to be pruned when transplanted to compensate for loss of roots during transplanting.

Mulch is important for fall plantings. Spread a layer 2 to 3 inches deep for trees and shrubs and 1 to 2 inches deep for perennials and ground covers. It is best to keep the mulch away from the crown or base of plants and the bark of trees and shrubs.

Good soil preparation is important for a successful planting of perennials. 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-lived, hardy perennials. After the large, showy late-spring blooms are finished, their neat foliage stays green until frost.

They do best in full sun; although they can tolerate partial shade, flowering will be reduced.

September is a good time to plant peonies as well as to divide and transplant existing ones. Dig around the plant so you can carefully lift the root ball. 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 small reddish growing buds that emerge from the top of the roots in spring and fall. When you replant, set the roots 1 or 2 inches below the surface of the soil with the eyes up.

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.

Keep the potted herbs outside for a few days in a partially shaded spot and keep their soil in even moisture. This will help them adjust to the move indoors. The shock from suddenly moving plants from outside to inside can cause some yellowing of leaves.

Once you move the herbs indoors, keep them in a sunny window.

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