Love Them and Leave Them

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Leaf Love: ‘Lazy’ Gardening for a More Robust Ecosystem

By Kate Small

Gardener at Marin Art and Garden Center

As the seasons turn and fall fades to winter, we are surrounded once again by magnificent, multi-hued foliage. Varied shades of scarlet, amber, and bronze brighten the shortening days. Many deciduous trees have already shed their leaves. Others still will shed theirs in the weeks ahead, further blanketing our landscapes. 

For many gardeners, this is a busy time of year: packing green bins to the brim each week, and filling countless brown yard waste bags. And yet, when it comes to managing fallen leaves, the most eco-conscious act is to take no action at all. More tidying now means fewer butterflies emerging in spring, fewer songbirds alighting in summer, and perhaps fewer fruits and veggies—that rely on insect pollination—to harvest from our edible gardens through the fall. 

For several years, the Xerces Society for Invertebrate Conservation has championed a #leavetheleaves campaign to spread awareness. The message is this: wherever possible, leave leaves to decompose where they fall. Do this for the health of your plants and the environment as a whole. 

Healthy Soil. Fallen leaves provide the same benefits as other organic mulches like wood chips or rice straw, and in some ways are preferable to these alternatives—more on that below. A layer of leaves holds moisture in the soil, limits runoff, provides some protection from foot-traffic compaction, suppresses weeds, and feeds soil organisms. Microorganisms, in turn, break leaves down into plant-available nutrients. When you leave the leaves, rather than interrupting the nutrient cycle by removing them, your plants will stay healthier with fewer added fertilizers. Fallen leaves are free. And no fossil fuels were burned to move them. A win-win.

Happy Pollinators. A blanket of leaves shelters a vast array of butterflies, moths, bees, and wasps through the winter. Some species overwinter as larvae, like the wooly bear caterpillar. Some species, including swallowtails, spend winter in a chrysalis designed to blend in with dried leaves, waiting for warming temperatures to emerge. Others, including the mourning cloak butterfly, hibernate as adults under dry leaves. Removing leaves will significantly reduce their populations the following spring. Ground-nesting native bees, some of the most efficient among the pollinators we rely on, can still access their nests through a leaf layer. Wood chip mulch, on the other hand, may leave them stranded.

Harmonious Ecosystem. Slugs, snails, centipedes, beetles, crickets, and countless other invertebrates thrive in fallen leaves. While these may not be among your favorite garden creatures, they are an important part of the food web. Myriad birds, lizards, and small mammals feast on them at a time when other sources of food are scarce, plus use fallen leaves themselves to make nests and hide from predators. Raptors and larger mammals, in turn, rely on the food source of small vertebrates. One interrupted link in the food web and there is a cascading negative impact on all.

Skip the Shredder. If you have places that leaves cannot be left to decompose, like on top of hardscape or where they would smother low-growing perennials, consider collecting these and spreading them elsewhere in the garden. Pile the leaves under trees and shrubs—taking care not to bury the root crown—or use them as mulch in your vegetable beds. When you do, leave them whole. Shredding leaves will shred overwintering pollinators along with them. 

Leaving leaves does not have to be an all or nothing approach. If this is new to you and you pride yourself on a meticulous garden, consider starting with one area to leave a little wilder this season. Of course, the more the better. The birds and bees will thank you. 

Further Reading:

From the Xerces Society, on more steps you can take this season to help insects thrive:

Nesting and Overwintering Habitat: For Pollinators and Other Beneficial Insects

From the American Museum of Natural History’s Center for Biodiversity and Conservation, on getting to know the wide range of organisms found under the leaf layer:

Life in the Leaf Litter

More to explore