Can I clean up my leaves now?
It’s a question hopping around social media chats: “Because I care for biodiversity, I have left my leaves through winter. Can I remove them now?”
For biodiversity, the answer is no. Leave leaves entirely and let them deteriorate. Sweep them away from walkways and off turf grass and leave them in plant beds. Do not shred your leaves.
Why leave leaves and plant stalks?
When we shred and cart away our leaves, biodiversity is going with it. You may have read that insect biodiversity is in steep decline. North American studies on monarchs and bumblebees illustrate that decline, paralleling the findings of other insect studies globally. A 2018 article in The New York Times pointed out that while certain insects are the charismatic megafauna of the insect world and “a whole insect world might be quietly going missing, a loss of abundance that could alter the planet in unknowable ways. ‘We notice the losses,’ says David Wagner, an entomologist at the University of Connecticut. ‘It’s the diminishment that we don’t see.'”
How long to leave leaves?
Critters like fireflies, native ladybugs and adorable spiders (check out jumping spiders) spend whole their lives in our backyard debris, not only overwintering, but living there all year long.
The story of the monarch butterfly migrating to Mexico may have created some confusion. The monarch story is notable because it is uncommon. Most insects overwinter in place. Diverse butterflies and moths overwinter in our garden debris as eggs, caterpillars and even as adults.
Moth and butterfly chrysalises and hibernacula often look just like leaves. Shredding and tossing all these critters with our leaves is such a desperate waste. With these insects are lost all the interrelationships they represent with plants, as pollinators, germinators, beneficial predators of destructive insects and more.
Tossing these insects leads us to added cost, carbon and toxins: We cart in mulch and add synthetic fertilizer in place of leaves, and apply insecticides and other chemicals in place of the natural predators that should be in our gardens. Insects are also part of the crucial foundation of a food web that feeds songbird nestlings and adult birds, mammals, fish, reptiles and amphibians, and all sorts of other insects.
How should I manage my leaves?
Do sweep your leaves off walkways and lawn. Leave them in wildflower beds, under shrubs and around trees. Remember to leave a few inches of space around the trunks of trees and shrubs to avoid holding moisture against the bark that rots the plant. Letting the leaves naturally decay feeds your garden plants and enhances your topsoil. Leaves are natural fertilizer.
If you must tear down stalks, wait till warm weather, and put them in a dry garden area, for example under shrubs, for any critters inside to emerge. The time you should remove your leaves or plant stalks is in the rare event a plant in your garden has a bad infectious disease.
Hopefully you would notice something amiss already from the condition of your plant. But authorities can help diagnose plant problems. Contact the plant clinic at the University of Illinois Extension or The Morton Arboretum. Many plant ailments resolve naturally. Holes in plants are of course normal: We want insects to use and eat our plants. Insects need to eat plants to live and flourish. Bumps on plants also are often normal galls, or insects that other beneficial insects can control.
Does leaving leaves make it harder for plants to emerge in spring?
Not for most plants. Native plants are used to leaves, so have no issue. Even cultivars and nonnatives generally do fine emerging through leaves: in my experience, peonies, irises, crocus, vinca have no issues.
Tulips have some trouble with dried leaves crimping their growth. It is simple just to free the caught tulip: Pull off the dried leaf if it does occur.
More info: https://climate-action-evanston.webflow.io/natural-habitat/home
Leslie Shad is lead of Natural Habitat Evanston.
Completely agree!
If nature didn’t want them to fall to the ground and to do what’s natural, nature would, I suppose, keep them on the trees year round or or float them up into the air like those environmentally contaminating helium filled party balloons.
I leave them on all winter and remove maybe half in some areas while leaving all of them in other areas as I go from year to year to see how it works..which, with one small area where the bee balm didn’t come up after leaving the leaves in place.
I am surrounded with oak trees, so the leaves can be 3 or 4 inches deep.