Prepare Your Perennials for Autumn

As autumn arrives, gardening fans will have to do some prep work to protect perennial plants. In general, if you live in a warm-winter area, do a basic cleanup 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.

Here are the essentials you need to dig into this fall.

Phases 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, day lily, other lilies, and 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.

Cut 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.

Don't Cut Back These

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, so consider leaving these. 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.

Dig Up Tender Perennial Bulbs

After the first frost when foliage begins to yellow and die, cut back the foliage. Then dig up 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.

Mulch Perennial Beds in Autumn

Buy mulch at a bargain price 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. 

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 when feasible, and supplement your indoor winter garden with blooms and small fruit trees.

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