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.
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.
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.
With thought out pruning, perennials can be timed to bloom in continuous waves. Spring blooming perennials should not be pruned until after flowering. Summer bloomers should be pinched in early spring. Perennials that bloom in the fall should be cut back by July 4.
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.
Prune foliage down to just a few inches from the ground and make sure to clear away any debris from the garden to help prevent disease and rot in the early spring. If perennials (like Bee Balm or Phlox) were diseased this past season, cut the foliage all the way down to the ground and don't compost it.
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.
Most perennials turn ugly as the temperatures drop and any plant that is diseased, infested, or otherwise in poor condition should certainly be cut back and disposed of rather than leaving them to over-winter. However, some perennials simply don't fare well if they are pruned too late in the season.
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.
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.
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.
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.
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.
Instead, wait until late fall. It's during the early fall (September and early October in my Pennsylvania garden) when the night-time temperatures start to drop, that the carbohydrates begin to make their way back down to the plant crown. Wait to prune back hostas until the leaves turn completely yellow or fully brown.
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.
Dividing Hostas in Fall
You should wait until night temperatures have cooled but while there is still time for divisions to grow new roots before freezing weather sets in. September is usually best in areas with cooler climates, October is okay for dividing hostas in warmer zones.
Divide fall blooming perennials in the spring because
Plants have stored up energy in their roots that will aid in their recovery. Rain showers that generally come along with the early season are helpful. Plants divided in spring have the entire growing season to recover before winter.
Always cut back to a leaf or part of the stem where you can see a new bud forming. Later in the season, when the plant begins to produce fewer blooms, you can just let them be. Let the plants stand during the winter to provide food for birds. In late winter, prune them back to the ground.
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.
Most herbaceous (i.e. non-woody) perennials die off above ground in the winter and sprout back up from the roots the next spring. Some of these have colorful fall foliage like trees and shrubs do, and are fun to watch as their colors change. Others turn ratty, slimy brown-black with the first rain.
Many factors influence the reliable return or the final farewell of perennials, depending on each plant's ability to withstand overly harsh conditions such as draught (Yes, draught happens in winter just as it does in summer.), insect infestation, late heavy frost, consistently below-normal temperatures for a lengthy ...