Leave perennials up for winter interest

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 your perennials when they start looking bad. It is also OK to cut the perennials back in the fall if you prefer a cleaner look for winter.

Any new perennials planted this year, and especially those installed in late summer or fall, should receive a layer of mulch for the winter. The freeze-and-thaw cycles in spring can push newly planted perennials out of the ground.

• Continue cutting your grass throughout the fall as needed, taking care to stay off the lawn when there is heavy frost present. Cold weather will eventually stop grass growth. Make your last cut of the year at a lower height of 2 inches.

• Terra cotta containers are best stored out of the elements for winter. When plants in these containers are finished for the year, dump out the growing medium and store the pots in a garage or shed so they are out of the rain. These containers absorb water and the freeze-and-thaw cycles of winter can crack them if they are left outside.

If you need to leave them outside over winter, then it is a good idea to elevate them above the ground, store them upside down and cover with a tarp to keep the pots as dry as possible.

• Any soilless mix from window boxes or containers can be discarded, mixed in a compost pile, blended into a garden bed or kept aside for one more year. If the growing medium is used for a second year, mix equal parts of the old mix with fresh soilless mix next year. Avoid reusing medium in containers that had any problems with disease.

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