In general, if you live in a warm-winter area, do a basic clean up of your garden beds and replace diseased or worn-out plants. Gardeners in all other climates need to keep plant roots from freezing and to prepare perennials for the spring.
Specific plants are mentioned throughout this article, but call your local garden center for a more complete list. Take a look at a video covering all garden tasks for this month. Okay, here are the essentials you need to dig into this fall.
First Phase of Fall Perennial Care
In the early fall, dead-head perennials and you may have flowers for several more weeks. The goal is to keep the flowers from forming seeds. Destroy any diseased or insect-ridden perennials and clean up leaves that have fallen to the ground. This may include columbine, delphinium, daylily, some lilies, peonies.
In the late fall, clear out anything that will be a determent to a beautiful spring garden, or that looks messy in the winter. This might include: anemone, coreopsis, delphinium, geranium, hostas, and phlox.
Cutting Back Perennials
Mid to late fall is the time to cut back the tops of plants. If you cut back too early, you may have some new growth. You want perennials to become dormant and to experience the cooler weather and shorter days. Later in October and November cut back plants that need it. For bushy perennials, cut them back by at least half. When perennials have finished the season, cut back stems to 6 to 8 inches from the ground. Cut back ornamental grasses in the fall unless you love to see the tall grasses in the snow. You might let the ornamental grasses hang around until late winter or early spring.
Plants that don't need to be cut back include: evergreens (or trim them a little bit after they bloom), alyssum, dianthus, lavender, creeping phlox, sedum, violas, and others. Fuchsia, hypericum (woody-stemmed perennials) should not be cut back, instead prune them in the spring. Coneflowers, asters, astilbe, sedum and other plants with seed heads will feed birds over the winter. Consider leaving these during the winter. Asters, coreopsis, Shasta daisies, poppies, and salvia have a group of evergreen leaves close to the ground. Leave these alone, but cut the dead leaves off in the spring.
Digging Up Perennial Bulbs
After the first frost when foliage begins to yellow and die, cut back the foliage, dig, and store tender perennial bulbs ( dahlias and gladiolus, for example) that can't survive the winter in the ground in a cold climate. When digging, be careful not to damage the underground bulb or tuber.
Mulching Perennial Beds in Autumn
Buy mulch at a bargain in the fall, spread it on your garden, and stockpile some for next spring. Or, use dried maple leaves, straw, dried evergreen boughs, and other compost. Apply loosely around the base of plants. Spread a 4- to 6-inch-thick layer around the beds. This releases nutrients to the plants and improves the soil. Here's a list of what to mulch from perennials.com.
Winter can be a time to enjoy the color and fruits of your indoor plants. Prepare your outdoor garden to hunker down through the winter months, move plants indoors, and supplement your indoor winter garden with blooms and small fruit trees.