Get Your Perennials Ready for Winter

How to Cut Back Perennials

Nov 10, 2017
Coneflowers: Winterizing Your Perennial Garden

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Prepare your perennials for winter! Most perennials can be cut down after the first killing frost; others can add interest or help birds and beneficial insects during the winter months. See our tips.

CutTING BACK Perennials

After several hard frosts, most perennials can be cut back. To cut back your perennials, use bypass pruners and make clean cuts through the stems of the plant. I usually leave 6-inch stubs so I can find the plants next spring. 

Plants need to be cut back after frosts to avoid disease and pest problems in the spring. Bee balm and phlox are prone to powdery mildew so cut them all back once they’re gone. Remove all hosta after a hard frost, including any leaves on the ground, as they harbor slug eggs. Other perennials to cut back include bearded iris, peony, daylily, veronica, sunflower, salvia, shasta daisy, clematis, columbine, catmint, and yarrow.

Don’t be in a rush and be sure until a few hard frosts. Even if the flowers or leaves are dead, the roots are reclaiming energy from the dying plant for healthy growth in the spring.

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Leave Some Winter Interest

Leave a few things standing for winter interest. The blackberry lily Belamcanda looks great until heavy wet snow finally knocks it down. Ornamental grasses add movement and sound to the landscape. I let the agastaches and coneflowers and rudbeckia stand for the birds to enjoy. Self-seeding plants will provide you with volunteers next spring to move to new spots or share with friends.

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Many perennials, like this penstemon, have already started to form leaves for next year at the base of the plant. When cutting back be sure to leave these rosettes of green.

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Some Perennials NOT To Cut

Some perennials (including the alpines above) and epimediums, hellebores, candytuft, primulas, dianthus, hens & chicks, heaths, and heathers are considered evergreen and should not be cut back in the fall.

This hellebore is considered an evergreen and should not be cut back in the fall.

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Do not cut back marginally hardy perennials such as garden mums (Chrysanthemum spp.).

Clean Up Debris

As with the vegetable garden, any diseased or bug infested plant material needs to go—far away. Don’t put it in the compost pile. Debris from things like rusty hollyhocks, peonies with powdery mildew, leaf-spotted delphiniums, and other fungal-infected flowers should be removed from the garden.

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Leaves from a peony infected with powdery mildew should not be composted.

Don’t Fertilize in the Fall

Fertilizing in autumn encourages new growth that will just get killed when cold weather hits. Compost is not considered a fertilizer; it is a soil conditioner so feel free to add that in the fall. If your soil test indicates that you need lime, it can be applied in the fall also.

Weeding

Before the ground freezes, do a final weeding. The more weeds you can get out now, especially those that have seeds, the fewer weeds you’ll have to deal with in the spring. Edge your beds for one last time and you’ll start the year with a neat and tidy look.

To Mulch or Not to Mulch

If you are growing plants that are hardy in your zone and live where snow cover is plentiful each winter you probably don’t have to worry about mulching your garden, though it’s always insurance to give them some extra protection. It’s newly planted perennials that are the exception. Definitely tuck some mulch around them for their first winter.

The purpose of a winter mulch is to keep the soil temperature even and prevent heaving of roots due to alternate freezing and thawing of the ground. Waiting until the ground is frozen before mulching is not only best for your plants but also discourages rodents from making a cozy home there. Use a mulch that does not pack down and smother your plants. Shredded leaves, pine needles, straw, or evergreen boughs are good choices. Snow provides the best insulating mulch, it goes down gradually and melts gradually.

Learn more about mulching your garden.

Watering the Garden

If you live where it has been dry this growing season, keep watering your garden until the ground freezes. Usually there is plentiful moisture in the fall but many areas experienced drought conditions this summer and the ground is dry. Plants that are water stressed will have a tough time surviving the winter.

The more work you do in your perennial garden this fall, the less you’ll have to do next spring.

See more about overwinterizing plants in the garden—from roses to rosemary.

About This Blog

Get inspired by Robin Sweetser's backyard gardening tips. Robin has been a contributor to The Old Farmer's Almanac and the All-Seasons Garden Guide for many years. She and her partner Tom have a small greenhouse business and also sell plants, cut flowers, and vegetables at their local Farmer's Market.

Reader Comments

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Cutting Back Plants for Fall

I've been told that butterfly bushes need to be cut back in the Fall. This is the first year that we have had a butterfly bush and I would like to know when to cut it back and how much to cut it back. Thanks!

Cutting Back Butterfly Bush

As soon as the foliage on the butterfly bush starts to die back (typically after a couple freezing nights), you can cut the stems down to the ground. Aggressive pruning will encourage more blooms, as butterfly bushes only bloom on new wood. Check out our Butterfly Bush Growing Guide for more information.

How far back should you

How far back should you cutback knock out rose bushes?

I would recommend only

I would recommend only pruning out diseased, dead, or broken canes at this time of year. A heavy pruning can promote growth and cause the plant to come out of dormancy and any new growth would be killed by cold weather. Wait until early spring to prune your plant for shape. At that time you can cut a mature Knock Out back by 1/3. Be sure to make your cuts just above a dormant bud. When shaping be sure to keep the top of the plant narrower than the bottom so sunlight can reach the base of the plant. Remove canes that cross and thin the center of the plant to improve airflow.

Very helpful information

Very helpful information.Thank you.

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