For most of us, the end of summer means yard and garden cleanup. I used to follow the same routine every year, cutting back stems and clearing out leaves. Then I found out that my tidiness was actually harmful, or even deadly, to the native bees and butterflies I worked so hard to attract.
Unlike honeybees, who have human keepers to care for them, native bees and butterflies need to find their own ways to survive the winter. Some bees burrow into the soil, while others hibernate in hollow stems.
Some butterflies survive winter as pupae, attached to twigs or dried leaves. Bumblebee queens overwinter in leaf litter and brush piles. By cleaning away the debris and mulching every bare spot, I was leaving my beloved bees and butterflies homeless ... or worse.
With a few changes, I stopped destroying pollinator habitat and started helping bees, butterflies, and other beneficial insects find safe homes for the winter and beyond.
Leave some bare soil
Most of Minnesota’s more than 400 native bee species are ground nesters.
Unfortunately, many of us use thick mulches in our gardens and landscapes. This is great for plants, but not so great for bees, who can’t dig through heavy wood mulches.
To help ground-nesting bees, keep some bare spots open for burrowing.
Leave some flower stems
About 90 species of Minnesota native bees are cavity nesters.
These bees hibernate in hollow stems and cavities during the winter and lay their eggs in these same places in the spring. By cutting and destroying stems in the fall, we take away potential homes for bees or kill their larvae.
Instead of trimming flowers in the fall, leave them standing to feed birds. In the spring, trim the dead stalks back, keeping stems 8-24 inches high.
New growth will quickly hide the old stems. Leave these stems in place through summer, winter and at least halfway through the following summer.
If you choose to trim flower and grass stems in the fall, keep them 18-24 inches tall.
Collect fallen stems and lay them in an out-of-the way place.
Leave some leaves and brush
Unlike ground and stem-nesting bees, bumblebee queens hibernate tucked away under leaves or brush. Only queen bees overwinter, while workers die in the fall. Queens are left to start new colonies in the spring.
To help bumble bees, leave small, undisturbed piles of leaves or brush in your garden or in a corner of your yard.
With just a few minor changes to your standard fall cleanup, you can help protect the native bees, butterflies and other beneficial insects that help our gardens grow. A little mess can make a big difference.
Watch a video on fall cleanup for pollinators
In this video, University of Minnesota Extension Educator Julie Weisenhorn demonstrates the pollinator friendly cleanup routine she uses in her own garden: youtu.be/TlZWfFHoUmk
Rebecca Holmlund is an Anoka County Extension Master Gardener.