Cleaning up flower beds can be done all season, but it’s a good idea to do a final cleanup in the fall. Some perennial plants look great during the winter, for example rudbeckia seed heads are decorative when topped with snow or ice. If the plants look OK, you can leave them intact.
Other plants die back after the first frost; the foliage becomes brown & messy. Trim back any stems or leaves and add them to your compost pile.
If any plants were diseased or had a lot of insect pests, cut the stems/foliage back to a few inches above the ground and dispose of the plant material in the trash, not the compose pile. This will help prevent a recurrence the following year.
If you have any invasive weeds such as Japanese Knotweed, Oriental Bittersweet or others, you can begin the removal process. Dig them up and/or use a herbicide. Be sure to follow the directions on the label of the herbicide, this will prevent overuse of and exposure to the chemicals. Remove smaller weeds or tree seedlings by hand to prevent them getting established next spring.
Finally add a layer of mulch of bark or leaves to the soil, a two inch layer is sufficient. The mulch conserves moisture and prevents ‘frost-heave’ where the freeze-thaw process forces plant roots to surface of the soil.
These steps will ensure a healthy flower bed for the following year.