Fall Cleanup to Protect Pollinators
By Nate Walton, Michigan State University Extension Master Gardener Coordinator
Along with all of the nationwide enthusiasm for protecting our pollinators have come some really important questions about exactly how best to do it. In some cases the questions are easier to answer because we have an abundance of scientific research, for example, on the effects of insecticides on pollinators. Unfortunately, to answer other questions, we are left with a scarcity of research and we are forced to make generalizations or to leave questions unanswered because, frankly, we don’t know the answer. The question of how to protect overwintering pollinators in our managed landscapes and gardens is one of the latter. Hopefully, all of this debate will inspire more scientific research, but in the meantime we are forced to make generalizations based on what little we know about the overwintering ecology of some of our flower-visiting insects.
It may seem early to be talking about fall cleanup, but the fact is that many of our pollinators in our area (the Northwest corner of Michigan’s Lower Peninsula) have already found a place to spend the winter by now. The remainder will be looking for their winter home in the coming months so now is as good a time as any to plan your yard and garden cleanup to protect pollinators. There is no one-size-fits-all solution for protecting our overwintering pollinators. “Pollinators” are an incredibly diverse group and each species has its own preferences for overwintering habitat and emergence timing in the spring. Also, the community of pollinators and how well they survive the winter depends a great deal on geography, climate, and even microclimates in your garden. Finally, the plants themselves in a lawn, perennial bed, and annual flower bed all have specific management needs to keep them at their healthiest going into next year’s season. All of these complications make it virtually impossible to craft recommendations that will satisfy all parties involved. It is up to you to make choices that optimize the protection of pollinators while also meeting your own objectives for your managed landscape or garden.
To Clean or Not to Clean?
The most important thing to keep in mind is that by creating overwintering habitat for pollinators in your managed garden space you are committing yourself to caring for those pollinators until next spring or summer when they “wake up” and continue their development. In other words, by creating habitat for overwintering pollinators in the fall, you run the risk of harming them in the spring unless you are very careful during your spring gardening activities. Alternatively, you could create habitat for pollinators in a part of your yard that is less heavily managed, where you perform neither fall nor spring cleanup.
When to clean?
In the garden space where you do like to tidy things up in the spring and fall, clean up early in fall rather than late so that you don’t risk attracting pollinators that are looking for a winter home. You can then choose to place the leaf litter and stem cuttings from your cleanup activities in another part of the yard to provide habitat for the pollinators there instead. Don’t forget to take extra care with plant material that may be harboring plant pathogens. If you had plants with signs of disease in your garden, you’ll want to separate their leaves and cuttings and destroy them to prevent re-infection of your plants next season.
What and how to clean?
Many of our pollinators in the Northwest Lower Peninsula of Michigan overwinter under the soil, attached to woody stems, or on tree trunks. These pollinators are not likely to be affected much by typical fall cleanup activities. Some bees and butterflies will spend the winter inside of or attached to the stems of some of our herbaceous perennials and ornamental grasses. If you are cutting these back in the fall, you can carefully bundle or pile the cuttings and place them in an undisturbed area so that those insects can complete their development normally in the spring.
A few species of moths and butterflies will choose the leaf litter as an overwintering site. If you don’t get around to performing fall cleanup until later in the season (see above), then you can remove the leaves carefully to an undisturbed area. Hand removal of leaves is not likely to cause much harm to the overwintering stages of pollinators. Gentle raking is probably okay as well. Avoid leaf blowers and leaf vacuums, as these are more likely to harm the overwintering stages of pollinators that are sheltered in the leaf litter and around the lower portions of landscape plants.
What about spring cleaning?
Check back with me in the spring for a follow up to this article. In the meantime, there is a wealth of information about how you can support pollinators by withholding pesticide sprays, providing flowering plants, nesting resources, and overwintering habitat, all available at migarden.msu.edu and pollinators.msu.edu.