Delaware Botanic Garden

Cross “clean up garden beds” from your to-do list this fall and you’ll do much more than save time. 

Cross “clean up garden beds” from your to-do list this fall and you’ll do much more than save time. You’ll save insects and save the plants and food webs they support, which saves animals further up the food chain. Entomologist Doug Tallamy counts cutting back on the fall cleanup as one of the ways we can bring nature home to our yards.

Here’s what to do in the garden this fall, what not to do and why it matters.

Fall garden

What stays

  • Perennials may have faded and dried, but they still provide shelter for birds that migrate through and overwinter in Lancaster County.
  • Seed heads provide food for wildlife.
  • The stems of these plants often house eggs for next years’ crop of beneficial insects, including native bees and katydids. Wait to cut down plants until late February or early March, Tallamy said in a talk in September.
  • The next generation of some insects don’t emerge until June. One way to find middle ground is cutting stems two feet above the ground, where most eggs can be found. Cutting stems and stacking elsewhere sounds like a good plan, Tallamy says, but it hasn’t been researched.
  • Not too worried about insects? You should, he says. Nature is made of millions of interactions. Without ants, there wouldn’t be woodpeckers. Without white turtlehead, there wouldn’t be the Baltimore checkerspot butterfly. Mowing down everything in the fall destroys next year’s insects.
White wood aster

What goes

  • Remove diseased plants to stop the spread. Plants provide habitat and food for bees and butterflies in the native pollinator gardens at Tanger Arboretum on the grounds of LancasterHistory. But this year, some of the bee balm and phlox had powdery mildew, so they were pruned and removed, says Lorri Schmick, an arboretum board member.
  • Cut back aggressive and invasive species. Keeping aggressive plants in check allows others to thrive. At Mt. Cuba Center, near Wilmington, Delaware, that means going after plants like white wood aster says assistant horticulturalist Raymond Carter.
Leaves

Leaves

  • Instead of raking and bagging leaves, use them as an insulating mulch for garden beds. Leaves are a wonderful natural mulch that enriches the soil as it breaks down, Carter says. The arboretum’s trees provide plenty of leaves for the pollinator beds, Schmick says.
  • Leaf litter is also where many caterpillars overwinter. Take moths, for example. In the fall, more than 90% of moth larvae drop from trees onto the leaves and soil below, where they pupate in cocoons, Tallamy says. Gathering and shredding those leaves harms those caterpillars.
  • An alternative to leaving the leaves is to compost them.

Keep neighbors happy

  • Mulch a 12-inch to 18-inch border around garden beds. It will give the area a tidy edge and make the drying plants look intentional, not forgotten.
  • Keep public-facing areas tidy and follow the no-cleanup tips in out-of-sight gardens.
  • Tell neighbors what you’re doing so there are “more people who understand that their gardens aren’t separate from nature,” Carter says.
Hairy bittercress

Fall garden to-do list

  • Fall is one of the best times to plant perennials, shrubs and trees. As long as perennials are planted by Thanksgiving and trees go in before the ground freezes, the plants will have time for roots to grow. Planting now means they won’t be stressed by heat and will receive plenty of rain by the time they are ready to sprout.
  • Remove winter weeds. For example, hairy bittercress emerges in the fall. Remove the plant now and you won’t have to deal with it in the spring.