Delaying Spring Clean Up to Help Overwintering Pollinators
Hello - I have seen the attached meme repeatedly over the last week or so on Facebook, Nextdoor, etc. I've done a lot of online searching for more information but I wondered what the Extension Service has to say about best spring clean up practices to support pollinators. I looked at articles from the National Wildlife Federation, NRDC, Sierra Club, the Ecological Landscape Alliance, and more. Regarding the information I found, one article specified to wait until daytime temps were consistently above 50 degrees (isn't that now?). Other articles went into detail about where various species nest and how to make your garden more hospitable, and while some did suggest delaying spring clean up a bit, there were no firm recommendations. I don't like the effects of this meme. Even though it makes a bold pronouncement without enough detail and it doesn't site a source, many people are taking it like it's an ironclad rule.
Washtenaw County Michigan pollinators
The answer to your question unfortunately is not a simple one. For one thing, we have a great diversity of pollinating insects and each species has different overwintering behaviors and locations. Also, the community of pollinators and how well they survive the winter depends a great deal on geography, climate, and even microclimates in your yard. Finally, the plants in your lawn, perennial beds, and annual flower beds will all have different litter management needs.
If you raked up leaves last fall, most of our pollinators will not be harmed by raking your lawn in the spring. However, the amount of leaves and other debris that you have in the spring is usually a matter of how you managed your leaves in the fall. If you left a lot of leaves on in the fall to provide habitat for pollinators, then you may have more leaves in the spring to clean up. In this case, you have to weigh the consequences of leaving a heavy leaf cover on the turfgrass. Dead leaves can smother the grass and you could lose a significant amount of your lawn if you don't break up that dense leaf cover. Fortunately, the majority of our pollinating insects (e.g. bees, moths, and butterflies) don't overwinter in the actual leaves. While they might benefit from some of the insulating properties of that leaf cover, they are actually under the soil or they are attached to woody stems, or tree trunks. If you mulch your leaves, or rake them up in the fall, then there will even less danger of harming insects in the spring. We should probably give these insects a little more credit for their survival abilities, a little light raking in the fall or spring is not going to harm most of them. Of course, there may be regional exceptions where individual species of conservation concern could be harmed by a particular practice. If you are worried about this, check with your local cooperative extension, conservation district, or DNR office.
Now, when it comes to cleaning up perennial or annual flower beds, this is quite a bit different from cleaning up your lawn. In this case, you do not run the risk of smothering desirable plants by leaving litter in the beds for a bit longer into the season. In some situations there may be disease inoculum or insect pests in the litter, which is why we often recommend removing those leaves as early as possible. However, this could be withheld if you are not struggling with disease or pest issues. Most perennials will benefit from the removal of litter from around their stems though, so it would be a good idea to clean out those beds before the growing season is in full swing.
If you are concerned about conserving pollinators, there is a wealth of information about how you can support them by withholding pesticide sprays, or providing flowering plants, nesting resources, and overwintering habitat, all available at migarden.msu.edu and pollinators.msu.edu.