It should be welcome news for weary gardeners. You’ve weeded, tilled, and toiled under the hot sun all summer long, and now — it’s time to stop. For many, however, the temptation to pick, pluck, and prune the landscape to make it neat and tidy for the winter is too hard to ignore. This impulse to “clean up our gardens for fall” has serious impacts on a whole host of pollinators and beneficial insects. All it takes is a weekend and some garden tools to accidentally wipe out whole populations of insects who have been hard at working hard in your yard all summer, too, provisioning their nests and making well-stocked winter homes for the next generation.
Pollinators need habitat in winter, too
Insect pollinators spend the winter in a variety of life stages (egg, larva, pupa, or adult) depending on the species. For example, adult native bees will have spent their lives in your garden drinking nectar, collecting pollen, and building their nests amongst your fruits and flowers. After hatching, the “new” bees will spend the winter in their nest cells as pupae, emerging as adults the following spring or summer. Lather, rinse, repeat.
This is why timing is critical. Habitat needs to be protected year-round.
If you cut down the stalks and stems bees are nesting in too soon in the spring, or while the bees are settling in for the winter, it is game over for your pollinator pals. If you apply a thick layer of wood mulch over the top of ground-nesting bees (70% of native bees are ground-nesting), or till your garden in spring or fall, then you’ve wiped out your best allies. That includes bees who emerge early in the spring to pollinate fruit trees and squash bees that live just beneath the surface of your garden and pollinate your pumpkins with aplomb!
Leaf litter, with its mix of bacteria, fungi, and invertebrates, is an ecosystem unto itself. It provides habitat for beneficial insects who in turn break the organic matter down into “garden gold” providing nutrients back to the soil. What we call “leaf litter” provides a wealth of overwintering habitat for invertebrates including slugs and snails, worms, millipedes, centipedes, spiders, beetles, and much much more! If you have children, exploring leaf litter together can be a great opportunity to engage them in a little scientific discovery.
Hidden in plain sight: butterflies, bees and moths
Unlike other native bees, bumble bees do not overwinter in their nests. Instead, new bumble bee queens emerge from their childhood homes in the fall and search for overwintering sites, burrowing into leaf litter and loose soil. That means mulching and tilling can disappear your bumbles.
For butterflies and moths, overwintering is even more complex. Lepidoptera overwinter in all manner of life stages depending on the species. Fritillary butterflies who host on violets spend the late days of summer seeking out violets with their antennae and laying eggs. The emerging larvae hide out in leaf litter, waiting for the plants to emerge the following spring.
The eastern black swallowtail (Papilo polyxenes) spends the winter as a pupa, hidden to all but the most scrupulous of observers camouflaged as a dried leaf or a broken off twig. It would be quite easy to miss when clearing canes and dried plant material from your garden.
We all know that monarchs migrate, spending their winter days as adults in Mexico and along the California coast, but did you know the resilient mourning cloak (Nymphalis antiopa) stays home, toughing out the winter between bark, in piles of dead wood, or in your garden shed?
We hope you’ll see, far from a dead and desiccated landscape, the fall and winter garden is teeming with life.
Fall cleanup do’s and don’ts:
Save the stems. Put your feet up, the pruners down, and grab a Pumpkin Spice Latte. Don’t cut canes, stalks, or other standing plant material which may house nesting bees or be providing anchors for overwintering pupae.
Leave the leaves. Where possible, leave leaves alone. If you must clear them from lawns and other areas, do not bag them and send them to the landfill – try to find a way to put fallen leaves to work!
Go no-till. Do not till soil where there might be ground-nesting insects.
Easy on the mulch. Opt for loose mulch like a nice layer of leaves. Avoid barriers that will trap ground-nesting insects like bumble bees, such as heavy layer of wood chips or rocks, or sheets of plastic and landscaping fabric.
Supply safe havens. Provide safe havens by setting aside undisturbed patches of habitat allowing leaf litter, standing dead twigs/stems, or other ground cover to remain. Unmanicured locations will provide the protected nooks and crannies that pollinators and other animals need for survival.
Notify the neighbors. If you must clean up your yard to comply with homeowners association rules or other local ordinances, consider sharing this blog, starting a conversation, and putting up a pollinator habitat or leave the leaves sign to advertise to the world that your “messy” garden is intentional habitat.
