Clean up the Perennial Garden in fall? Or not?

Whether or not to cut down and clean out the perennial gardens in fall has long been debated. And many of us have changed our minds in both directions over the years.

Winter Garden by Midwest Gardening.jpg

In recent years most of us have come to agreement on a middle ground when discussing cleaning out our perennial and annual gardens. If nothing else I think we all agree that the answer is not all or nothing. We no longer routinely cut everything down and rake it all up, but we don’t let everything stand through winter either. Several things should be considered when you make your choices.

Reasons NOT to clear out the perennial gardens in fall:

  • Leaf litter adds much needed insulation for your plants in cold regions.

  • Leaf litter helps feed your soil as it decomposes and encourages needed microbes and earthworms.

  • Spent plants help collect and hold snow for added insulation against severe cold.

  • Leave stand biennials and self seeders to allow proliferation.

  • Native bees over winter in little cracks, crevices or hollow stems.

  • Some butterflies overwinter as adults in leaf litter, or under tree bark. Caterpillars roll up in a leaf or a seed pod and a chrysalis might be found hanging anywhere.

  • Ladybugs prefer to nestle under just about anything rather than resort to coming in your house.

  • Other predatory insects that get rid of the bad guys in our gardens also nestle in under garden “litter”.

  • Birds that stay the winter feed off all these hibernating insects, so be sure you have plenty!

  • Pile up fallen branches and twigs to shelter small birds.

  • Colorful berries, seed pods, dried flower heads, all add beauty, texture and interest to your winter garden.

  • Enjoy watching the birds, hawks, and owls as the hunt in your garden habitat.

Reasons you should clear out SOME perennials in fall:

  • Clean up and divide overcrowded spring and summer blooming perennials.

  • Clean up and clear out space to plant spring blooming bulbs.

  • If your soil is poor and must be replenished with large amounts of compost and amendments periodically, completely clear a section each year.

  • If you were plagued by insect pests you should probably clear afflicted plants completely. Cut them back and dispose of foliage that may harbor eggs and will expose and discourage slugs.

  • Rodent pests thrive under the cover of over wintered plants. Removing some will expose the critters to predators.

  • Foliage infected with fungus, mildew or any disease should be removed to prevent spores from harboring in the soil over winter.

  • Remove rampant self seeders, or at least thoroughly deadhead.

  • Aggressive weeds are more easily seen and removed if plants and foliage are removed. If your gardens are overrun with tree seedlings, rampant seeders or invasive perennial weeds you might need to clear the beds to help eliminate them.

  • You wont trample unseen perennials just coming up in spring

Remember that your edible gardens have different needs and will need slightly different maintenance practices. See the article Feed the Soil in Fall for specific information.

Trees and shrubs of course have specific pruning needs at specific times, but we have some options with our perennial plants. Here is a brief guide to considering what to cut back, or not, in fall and why:

  • Cool season grasses are gorgeous swaying in the breeze in fall and winter so cut them back in spring. They also host loads of birds beneficial insects until spring.

  • Young and marginally hardy plants should be left standing to collect snow for added insulation to help them survive severe cold.

  • Perennials that turn black and ugly can be removed if you prefer. However don’t overlook any benefit of leaving them.

  • Every single bit of diseased or insect infected foliage should be cut down and disposed of.

  • If you live in a very wet region you may want to clean out leaves that pile up in the perennial beds to prevent rot and fungus. Shred the leaves and use them like mulch instead.

  • Perennials to generally leave over winter:

Cranesbill Hardy Geraniums - Dianthus - Hellebores - Heucheras - and any low growing evergreen or semi-evergreen perennials.

  • Perennials to generally cut back in fall:

Columbine where leaf miner is a problem - Hosta if slugs are a problem - Iris where iris borer is a problem - Painted Daisy may rot in wet winter soil - Bare stalks that provide no benefit - Foliage plants such as Hosta and Ligularia) that are a mushy mess in spring -

One very important tip when you are cutting down perennials - be sure to leave a few inches so you know where they all are in spring! You don’t want to trample them or dig into them before they become visible. I wait to remove the old plant remains until growth has started in earnest. For me, this is one of the more important reasons not to cut anything back in fall. Otherwise I have kids and dogs and a husband walking all over them!

Sharon DwyerComment