Leave the Leaves this fall season

During the early winter months, the colorful fall foliage we enjoyed just days before begins to find its way into our yards and lawns. For some, these leaves become an eyesore, but for the bugs that stay with us throughout the winter, they play a vital role.

Why leave the leaves?

As your gardens fade into winter sleep, all the lovely insects you have kindly nourished need you to do next to nothing. Invertebrates rely on fallen leaves for insulating cover when days turn cold. Their ideal shelter is accumulating throughout the fall and early winter, right in your yard.  

Most butterfly and moth species overwinter in the landscape, as an egg, caterpillar, chrysalis, or adult. Bumble bees, spiders, snails, worms, beetles, millipedes, mites, and more also rely on leaf litter for protection. These animals, in turn, are food for chipmunks, turtles, birds, and amphibians.  

“We have to think of caring for nature as a four-season activity,” says Chris Hartley, Science Educator Coordinator at the Sophia M. Sachs Butterfly House, a branch of the Missouri Botanical Garden.

Wherever these insects emerge in spring, they will pollinate promptly with each flowery meal. Awakening bugs and garden thrive. Your chore-free fall can naturally re-weave the Web of Life underfoot without lifting a finger. Leaving the leaves? What’s not to like? 

A marble orb-weaver spider (Araneus marmoreus) rests on a fallen leaf at Shaw Nature Reserve. Photo by Matilda Adams/ Missouri Botanical Garden.

What happens when you don’t leave the leaves?

Do you wrestle with your training (and guilt) to keep a tidy lawn? Common fall chores like raking leaves and disposing of them can make it harder for bugs to survive the winter. 

Families examine fireflies during the Firefly Festival at the Sophia M. Sachs Butterfly House . Photo by Sundos Schneider/ Missouri Botanical Garden.

Hartley says fireflies are a good example of how disposing of leaves can hurt a bug population. 

“Many visitors at the Butterfly House ask us why they don’t see as many fireflies as they did when they were growing up,” Hartley said. “The answer largely has to do with the loss of undisturbed forest land and its leaf litter habitat.  Fireflies spend at least one and sometimes two winters as a larva that lives in leaf litter.  People can make a huge impact by creating leaf litter habitat and leaving it undisturbed in their yards.  Fireflies will benefit, but so will pollinators, predators that control pest bugs, and many other beneficial insects. “

Hartley says rather than bagging and disposing of leaves, he encourages people to rake them up and put them into their garden beds.  The leaves will serve as mulch for the plants and the bugs in their yard will overwinter in the leaves. 

It’s also important to not use insecticides in gardens throughout the year. Even one application of pesticide can undo all the good you start by setting up a good habitat.  

“Even a one-time use of pesticides can counteract all the good done by leaving their leaves in place, ” Hartley said. “Much better to use no pesticides at all, and focus on other methods of pest control.” 

Maintaining healthy lawns and gardens with leaves

In the fall of 2023, the City of Webster Groves is asking residents to evolve what their ideal lawn looks like with encouragement from the community’s Sustainability and Green Space Commissions.  

Graphic by the City of Webster Groves/

Webster’s campaign to Leave the Leaves – the first citywide effort in our region – joins a human movement toward ecological best practices. It follows the city’s No Mow April campaign, an initial success this spring poised to expand in 2024 with neighboring cities considering joining in.  

“Raking or mowing fallen leaves cuts the overall biodiversity benefits of your pollinator plantings,” says Green Space Commissioner Carrie Coyne. “But you can modify leaf-moving to suit your situation. For example, if leaves in your front yard would drift into a storm drain, move those off the turf, onto planting beds or in rings around your trees. Pile leaves as a donut, pulled away from the tree trunk out to the drip line, the branching outer perimeter.”  

Webster offers colorful signs, sold at the Recreation Center, to show that your leaf-largesse is purposeful, not lazy. QR codes on these signs connect to the city’s website, where FAQs are posted with a link to send public questions to the Green Space Commission. The campaign encourages conversations, in person and through social media. 

“Be mindful of your neighbors,” says Coyne. “If they love clean, crisp edges, move your leaves away from your property borders. Eco-logic is considerate of others: insects, plants, and people. Having a conversation about your leaf-leaving will educate – and mitigate neighborhood concerns.” 

Both the Webster Groves Green Space Commission and the Garden’s Horticulture Answer Service field resident concerns about potential damage from leaves left on the turf.  

“Turfgrass that gets covered with leaves in the fall can handle about 10-20% coverage and still be OK,” says Laura Chaves who coordinates the Horticulture Answer Service. “More than that and you’ll likely have dead areas in spring.”

Many fans of Leave the Leaves are also growing beds of native plants around the yard, as biodiverse alternatives to lawn, which can then serve as a landscape accent.  

Photo by Kristina DeYoung/ Missouri Botanical Garden.

“When turf is maintained as a pathway, seating or playing area, or border around native plantings, you can move leaves off the lawn to other areas of your yard, compost them, or mulch them with the mower into dime-sized pieces, so the turf is still clearly visible,” Chaves advises. “This will recycle leaf nutrients and add organic matter to your soil.” 

How leaves are handled at the Garden

An aerial view of the Victorian District show the beautiful fall foliage and falling leaves at the Garden. Photo by Cassidy Moody/ Missouri Botanical Garden.

Garden visitors may be curious about work on leaf removal by horticulture staff and volunteers. Daria McKelvey, Education and Outreach Supervisor with the William T. Kemper Center for Home Gardening, shares these key reasons for removing leaves from paths and grassy areas:

“The first reason, is to prevent leaves from piling up on the turf grass and smothering it,” says McKelvey. “As you know, we have a lot of trees – 1,105 to be exact. From early fall through mid-November, our wonderful trees are constantly shedding leaves that, if left on lawn areas, would kill our grass – which is part of Garden aesthetics.”

McKelvey says blowers are used to manage leaves for safety.

“One of the first morning jobs our horticulturists do is blow off the paths, so there are no walking obstructions,” McKelvey says. “Piles of packed, wet leaves can make the path slick, conditions for someone to slip and fall. Or leaves may hide other debris, such as acorns, fruit, and twigs which people can slip or trip on. We make sure paths are clear so visitors can safely enjoy the Garden.” 

Sustainability is of equal concern for the horticulture staff.

“We’ve been testing electric blowers in the Kemper Center Demonstration Gardens,” McKelvey reports. “They are smaller and not as powerful as our gas-powered blowers, so they aren’t sufficient for clearing large paths. But they seem to work well for smaller areas. They run on rechargeable batteries instead of gas and are much quieter.”

Leaf removal from the Garden is done on a garden-by-garden basis.

“We have varying shapes, sizes, and plantings,” McKelvey explains. “Design of a garden affects the decision to leave leaves or not. For example, we do not rake leaves from the Woodland Garden or Kemper Native Shade Garden, areas that mimic forest environments. But if leaves are left on the gravel dry-garden beds in Seiwa-En, the Japanese Garden, you can no longer see the raked wave pattern that is meant to be enjoyed in this type of space.” 

Garden staff pose around the compost pile at the Garden. Photo by Jean Ponzi/ Missouri Botanical Garden.

While Garden staff do rake or blow leaves, they don’t just discard them or throw them away. Instead, they are added to the massive back-of-house compost pile to break down. Composted material is then re-used to mulch all 79 acres of Garden beds.

This helps control weeds, provides nutrients to plants as the mulch breaks down, and helps retain soil moisture for tree and shrub plantings throughout the year. It’s nature’s expert practice of zero waste, working in partnership with Garden teams, right on-site. 

Is the practice of Leaving Leaves right for you? 

Fall color of the fallen leaves of the Japanese maple (Acer palmatum ‘Satsuki-beni’) tree. Photo by Tom Incrocci/ Missouri Botanical Garden.

“When Garden visitors ask about leaving fallen leaves,” McKelvey says, “I encourage striking a balance between upkeep and the needs of the natural environment. Since no two gardens are alike, and everyone has different goals and growing conditions, I tell people to do what you can. Strive to implement more environmentally friendly practices and work within your limits. Start out small, make reasonable changes to the way you garden. Once you see the benefits, expand. Every bit helps in the grand scheme.” 

Trees, native insects, and soil will all benefit from this guidance, as we humans act on nature’s examples. 

“Forests are self-mulching!” Corin Purcell of Webster Groves reminds us. “Leaves provide free, healthy nutrients that trees need. When we follow forest expertise and let fallen leaves decay, they add organic matter back into the soil, so you don’t need to fertilize. Microorganisms, the life in soil, need food and nutrients all the time. Everybody’s nourished, everybody thrives – and you pay less and do less work.” 

“Mowing and blowing use fossil fuels and make neighborhoods noisy,” says Webster’s Carrie Coyne. Purcell adds, “We can improve our quality of life, along with ecological health, by letting Nature manage the season-ending work of fall.”  

Enjoy some autumn rambles in the hours you reclaim from raking and mowing – and let nature nourish you! 

By Jean Ponzi, Green Sources Manager with EarthWays Center.

Thanks for the expert information from Chris Hartley, Science Education Coordinator; Corin Purcell and Carrie Coyne, Webster Groves Green Space Commission; Laura Chaves, Horticulture Answer Service Coordinator; and Daria McKelvey, Education and Outreach Supervisor.

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