Doing Less in the Garden: The Ecological Benefits of Leaving Things Be
- Rachel Emus
- Oct 14
- 6 min read
Plant stems and leaves are vital elements of a native garden. If you’ve planted native species to attract pollinators and other beneficial insects, you’ll also want to provide winter habitat to sustain their full life cycle. This article explores the benefits of doing less in your garden by resisting the tradition of “fall clean-up” long embraced by conventional ornamental horticulture. By leaving plant stems, seed heads, and leaves in place over winter, you’ll provide essential habitat for overwintering insects, enrich your soil, save money on mulch, add beauty and interest to the winter garden, and reclaim valuable time for yourself.
Although a few insect species migrate, the vast majority remain in Maine through the winter,requiring safe overwintering sites. Many hollow or pithy plant stems provide places for cavity-nesting insects, such as small carpenter bees, to call home. In your Maine garden, this might include stems of joe pye weed, wild bee balm, swamp milkweed, mountain mint, and other natives.
Leaving perennials standing through winter benefits hibernating insects (and the birds that feed on them) as well as us gardeners who enjoy the distinctive beauty of seed heads in the winter garden. Without seed heads, you’ll miss out on the free “volunteer” plants that self-sow throughout the garden. If you’d like to prevent certain species from spreading, simply remove those seed heads and compost accordingly (in the NGBH garden, we deadhead a lot of our Antennaria plantaginifolia before it goes to seed). Otherwise, leave them be and enjoy watching your garden evolve as plants multiply over time.
Retaining seed heads through winter provides a vital, protein-rich food source for non-migrating birds such as goldfinches, chickadees, titmice, and nuthatches. Native species like goldenrod (Solidago spp.), aster (Symphyotrichum spp.), sunflower (Helianthus spp.), thistle (Cirsium spp.), and coneflower (Rudbeckia spp.) produce and retain an abundance of small seeds that birds eagerly consume throughout the colder months.
Many species of insects rely on leaf litter to complete their life cycle. In the case of moths, 94 percent of species rely on the leaf layer to complete their lifecycle. Great spangled fritillary and woolly bear caterpillars tuck themselves into leaf piles for protection from cold weather and predators. Luna moths and swallowtail butterflies camouflage their cocoons and chrysalises to resemble dried leaves, allowing them to blend in with the leaf layer. Firefly larvae live in moist soil and leaf litter. At the end of summer, queen bumble bees burrow only an inch or two into the earth to hibernate for winter and welcome the protection provided by a thick layer of leaves.
While providing essential habitat for insects, fallen leaves also benefit gardeners by serving as a free, nutrient-rich mulch. They supply vital plant nutrients and organic matter that improve soil health as they are decomposed, slowly releasing nutrients and micronutrients not typically found in commercial fertilizers. Because leaves are relatively light and delicate, they are broken down quickly by fungi, microbes and invertebrates, making nutrients more readily available to plants than heavier mulches such as shredded or chipped wood. In addition, they help conserve soil moisture, moderate temperature extremes, prevent erosion, and store carbon. A recent University of Maryland study found that soils in areas where leaves are left to decompose naturally hold up to 32% more carbon.
The area under a tree is an especially critical place to keep leaves since many butterfly and moth caterpillars drop down from trees into the leaf layer to pupate and overwinter. In addition, research shows that leaves left under the trees they fell from have a “home field advantage,” where they are decomposed faster and release more nitrogen than if they were applied elsewhere.
A common concern among gardeners is that plants can’t push through thick layers of leaf litter. However, many woodland natives—including delicate spring ephemerals such as trout lily and squirrel corn—are well adapted to these conditions and have no trouble emerging through two to six inches of leaf cover. For those concerned about leaving leaves on their lawn, a thin layer of leaves is healthy for grass.
When and Where: Stem Cutting and Leaf Moving
In the fall, NGBH volunteers rake leaves off of paths (where they can lead to unsafe accessibility conditions) and into garden beds. These leaves remain in place throughout winter and into the next growing season, where they suppress weeds, retain moisture, and eventually are broken down to enrich the soil. Leaves that are donated from trusted sources are sometimes shredded which enables them to be broken down faster. This material can provide that satisfactory “cue to care” when used as a mulch border in garden beds. It’s important to keep in mind that when leaves are put through a shredder or mower, it comes at an inevitable cost to insects.
In winter or early spring, if some of our giant (and highly visible) Joe Pye weeds have toppled, they may be cut back strategically to create “stem stubble.” Otherwise, we start to selectively cut back perennials with hollow stems in mid to late May, leaving 8-24 inches of stem to provide nesting habitat for native solitary bees. By summer, this stubble blends naturally into the garden and is retained into the following season.
The longer you can wait in spring to cut back last year’s vegetation and remove leaves, the better. The Xerces Society recommends asking yourself the following questions before tidying up your garden:
Have I put away my snow shovel, mittens, and winter coats?
Have I paid my taxes?
Are apples and pears finished blooming?
At NGBH, we experiment with practices that challenge traditional horticultural habits that may no longer serve today’s ecological goals. For those who prefer a tidier look but still want to support insects, a balanced approach can work: keep the first few feet of your garden neat and let the back remain a little wilder, or dedicate certain areas of your yard as wild zones. Every garden has the potential to become more welcoming to our community’s smallest members.
In Summary:
The best option for wildlife is to leave leaves whole wherever they fall. If leaves need to be moved, do it early and rake them into your gardens, around tree bases, or in naturalized areas on your property. If you have more leaves than yard square footage, consider using vertical space by building a circular wire fence compost bin for leaves.
Leave plant stems and seed heads over winter because they are beautiful and provide food for birds and habitat for insects.
In late spring, cut back hollow and pithy perennial stems to 8-24 inches and leave that stem stubble standing for a couple of seasons. Leaving the cut stems on the ground nearby can allow overwintering insects to complete their lifecycles.
Embracing just a few of these practices in your landscape is better than nothing!
What You Can Do This Fall
Irrigation: Be sure to water fall plantings if conditions are dry so that they enter dormancy well-hydrated.
Protect newly planted tree and shrub seedlings from wildlife damage. This video from PennState Extension provides an overview.
Prepare new beds for future planting by smothering grass or weeds with layers of recycled corrugated cardboard or thick layers of newspaper, then put mulch on top.
Mulch any exposed soil, or top off mulch that may have thinned out (try using leaves this year!).
Cover cropping: Green manures help build soil tilth and fertility. Learn when and what may be appropriate for your garden: Bulletin #1170, Cover Cropping for Success.
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"For those who prefer a tidier look but still want to support insects, a balanced approach can work: keep the first few feet of your garden neat and let the back remain a little wilder, or dedicate certain areas of your yard as wild zones. Every garden has the potential to become more welcoming to our community’s smallest members."
I love this! It's a great way to encourage us all to do what's best for natural systems without shaming us for not being "all in" when it comes to our desire for some groomed spaces. Thank you!