Cutting back perennials in the fall is not only a great way to keep flowerbeds looking neat and tidy through winter, but it also aids greatly in keeping plants vibrant and blooming the following year. Removing spent foliage and blooms helps a plant focus on recharging it's roots and resources.
To prevent the disease from returning the following year, we suggest cutting the plants back in the fall and removing any debris – no matter the variety! It will give your plants a clean start next season. *Destroy any foliage with symptoms of powdery mildew and disinfect pruners before trimming other plants.
It's important to cut back foliage in the fall to protect flowering plants from disease and give them a clean start for regrowth as winter starts to turn into spring. However, there are some plants you can keep around through the winter since they benefit wildlife and still offer visual interest for your home.
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.
A good rule of thumb is that if the plant blooms on new growth, it can be pruned in winter, before the new season's growth begins and after the final bloom of the year. Be careful with spring-blooming shrubs—those usually can't be pruned in winter without damaging the flower buds and ruining the blooming season.
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.
Don't shear the branches of spring flowering shrubs (Forsythia, Lilac, New Mexico Privet, Spirea, Flowering Quince, and others). These shrubs produce flowers on last year's wood, so removing old growth will reduce or prevent flowering. These plants should be pruned immediately after they are done blooming.
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.
It's best to get any large amounts of pruning done during the spring or summer, when your plants are getting more sunlight and are actively growing. Trimming off a large amount of leaves, branches, or anything that will cut back a sizable amount of your plant, is best done during this time.
When to Cut Back Hostas. 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 you want to prune in fall, wait until trees drop their leaves and are dormant—usually October or November. After leaf drop, you can see the tree's structure and identify disease and insect problems more easily.
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 rule on fall pruning is, generally speaking, don't prune in fall. But there are a few trimming tasks you can take on with confidence, provided you approach the job with self-control and a plan. The timing window for these pruning chores is from Thanksgiving to the New Year.
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.
Shrubs prone to ice damage like wax myrtle and butterfly bush might be reduced in late fall or early winter to avoid breakage. Light thinning or shaping can be done almost any time, including fall, on shrubs that have developed uneven growth since their last shaping.
During the fall and winter, after the temperature drops, most trees, shrubs, grasses and flowers go through a dormant period, where they are not growing as many new roots. Instead they are storing energy in the roots to be used during the next growing season.
DON'T prune during fall.
This can weaken and damage the plant—especially if there's an early frost.
October is a good time to plant shrubs because the cooler temperatures of fall aren't as stressful on plants. When the air temperature is cool but the soil still retains some warmth, plants are encouraged to put out root growth.