Cutting old and diseased foliage in the fall helps a perennial jump right into new growth come spring. But some plants need their foliage for protection over the winter and instead should be pruned in the spring. Know your plant's particular care requirements for the best results.
Some perennials, like hostas, peonies and daylilies, need to be pruned in fall to avoid winter damage. Plants like these should be pruned after the first few frosts in late fall or early winter. Other perennials like mums and coneflowers are better off being pruned in spring just before new growth comes in.
Also, do not cut back hardy perennials like garden mums (Chrysanthemum spp.), anise hyssop (Agastache foeniculum), red-hot poker (Kniphofia uvaria), and Montauk daisy (Nipponanthemum nipponicum). Leave the foliage. It's important to protect the root crowns over winter.
It's common to think that everything should be chopped down to the ground in the fall, but some perennials actually need their foliage to protect new shoots through the winter. Other varieties offer up important habitat for local wildlife and some perennials provide height and interest through the winter months.
Perennial Flowers: Most perennial plants do not suffer frost damage and do not need to be covered. Frost sensitive perennials include Hostas and Bleeding Hearts. They should be covered to protect their foliage and flowers. Cover any blooming or budded up perennials.
2. Perennials and shrubs that are in your zone or one colder can be overwintered in an unheated garage, buried in the ground, or transplanted. 3. Perennials and shrubs in containers will need water through the winter but should not be kept wet.
Q: When is the best time to cut back in the fall? A: “When they start to look too ratty for you and before the fresh new growth begins,” says Sarah. For plants that are frost-sensitive, wait until after the plants have gone through several hard frosts to ensure they're dormant before cutting back.
The process of trimming back plants is the same for nearly all perennials. Begin by cutting the plant back to 3 to 5 inches above the soil line. Using a sharp pair of pruners or hedge trimmers, cut off all of the foliage and stems.
Mulching Tender Perennials
As with extra mulch, place the protective layer late in the fall season and remove it in early spring. A 6- to 8-inch-layer should be adequate for most perennials.
Transplant perennials when the weather is cool, even a little rainy, if possible. Early spring and fall care are best times for transplanting. Then the weather is cooler and the plants are not using as much water. “However, don't move or transplant perennials while they are in bloom,” he says.
Many gardeners cut back their perennials much too soon. There are nuances specific to certain perennials that dictate whether it is better to cut them back in fall or spring, but the general rule I like to follow is to only cut back perennials that start looking bad in fall.
As a general rule, hostas should be cut back in the late fall. Start with leaves that have wilted or turned brown. Healthy leaves can stay a bit longer to help the roots store needed energy. If 25% or more of the hostas is dying, you will know it is time to cut it back.
If your perennial blooms in the spring or early summer, it should be transplanted in the fall. If your perennial blooms in the late summer or early fall, transplant it in the spring. Remember that when transplanting in the fall, the perennial needs to be in its new location about six weeks before the first hard freeze.
At any time during the warm season it is okay to cut back dead or ugly foliage. When winter has arrived, and your perennials have either died back or stopped growing, you can remove all dead foliage. Then apply an inch or two of compost or mulch around plants. Leaves work great for mulch as well.
Cutting back of dead or dying top growth is the only maintenance that is needed for winter preparation. Cut the stems down to the ground, or to the basal growth if you are gardening in the warmer hardiness zones. Alternatively, the flower stems can be left to cut back in the spring.
The best time to apply winter mulch is just after the first hard frost. By putting mulch down at this time, you will help stabilize the temperature of the soil right around freezing. Applying mulch too soon may delay freezing and encourage heaving and thawing.
But when should hostas be cut back? Hostas should be cut back in late fall. Healthy hosta leaves can be left on the plant in early fall to capture much-needed energy, but all leaves should be trimmed off after the first frost to deter slugs and other pests from making your hosta their winter home.
Daylilies are best cut back in autumn, once the leaves have had a full growing season on the plant. While there are some evergreen types of daylilies, most are herbaceous, meaning that the leaves die back in the wintertime and sprout anew in the early spring.
Perennials. The newly emerged growth of most perennials can tolerate temperatures in the low 30s and upper 20s °F. This includes many early emerging perennials such as bleeding heart, daylily, catmint, and columbine. In most cases, early leaf growth on these plants will be just fine with cold temperatures.
Any gardening expert will tell you, (contrary to what you may believe) that pruning encourages new growth just when the plant is trying to go dormant and new growth doesn't have enough time to harden before the first frost and freezing temperatures hit. Pruning at this time of year will severely weaken the plants.