Before winter, remove all diseased debris and broken branches from your flower garden. Discard any remaining annuals.
Recommended perennials to cut back in fall are: bearded iris; monarda (bee balm) unless it is new growth; gaillardia (blanket flower); nepeta (catmint); columbine; daylily (now or spring); bush clematis; helianthus; hollyhock; ligularia (now or spring); penstemon; peony; and helianthus.
These perennials are recommended to leave for spring cutting: asclepias (butterfly weed); chrysanthemums (mammoth mums); and heuchera (coral bells).
Birds will appreciate it if you leave echinacea (cone flowers) and rudbeckia (black-eye Susans) or any other seed producing plants standing through winter.
Soon the snow will be gone and it will be time to start cleaning up your perennial garden. First remove old foliage from perennial plants. Cut the stalks back to about 1/2 inch above the ground unless it is a crown plant, i.e. sedums, coral bells, etc. Only dead and damaged leaves need to be removed from the crown plants. Cut back your perennial grasses to about 3-4 inches above the ground if you have not already done so. Maybe leave a few blades of this dried grass behind for the birds to build nests. Next rake up all the old garden debris and matted leaves as this matter is a great hiding spot for slugs and insects plus it harbors disease. Dig out weeds. For healthier plants with more blooms consider putting down a thin layer of compost followed by a time-release fertilizer. Now sit back and enjoy your future blooms.