The Science Behind “Leave the Leaves”
Each fall, as golden and red leaves begin to pile up, many of us feel the urge to tidy. But research is showing that what looks “messy” to us may actually be essential to the life in our gardens.
A new study published in Science of the Total Environment (DOI: 10.1016/j.scitotenv.2025.181012) confirms what ecologists and gardeners have long suspected: removing autumn leaves dramatically reduces insect diversity and abundance in residential yards.
What the Data Shows
Researchers compared suburban yards where leaves were cleared in the fall with those where they were left to decompose naturally. The results were striking:
Yards where leaves were removed had ~17% fewer spring-emerging arthropods overall.
Populations of butterflies and moths (Lepidoptera) declined by about 40–45% in abundance and diversity.
Leaf removal disrupted populations of parasitoid wasps and other beneficial insects, showing that the effects ripple through the entire food web.
Under just one square meter of retained leaf litter, thousands of insects emerged — from caterpillars and beetles to spiders and pollinators.
The researchers also found that many species don’t emerge until early summer, challenging the common advice that it’s safe to clean up once temperatures reach 50°F. That rule of thumb, it turns out, isn’t supported by data.
These findings make one thing clear: those fallen leaves aren’t debris — they’re habitat.
Why It Matters
Butterflies, moths, bees, and beetles rely on fallen leaves for winter shelter. Many species lay eggs or pupate in the leaf layer; others use it for insulation against cold. When we rake, blow, or bag leaves, we’re often removing next year’s pollinators before they ever have a chance to emerge.
And because some insects remain dormant until summer, premature spring cleanup can still disrupt these life cycles—even if temperatures are mild. Insects are the foundation of our ecosystems, feeding songbirds, enriching soils, and keeping natural systems in balance. By keeping leaves in place longer, you’re directly supporting this web of life.
What This Means for Your Garden
At Summersweet Design, we focus on creating abundant, layered gardens that support both people and wildlife. The research reinforces that how we manage our gardens in fall and early spring has long-term ecological impact.
Here’s how to apply “leave the leaves” at home:
Keep leaves in garden beds. Let them stay beneath native shrubs, grasses, and perennials where they’ll protect roots and shelter insects.
Rake smart. Move leaves off paths and turf areas, but into corners, under trees, or onto naturalized beds.
Skip shredding. Shredders and blowers destroy the very creatures we’re trying to protect. Gentle raking—or leaving leaves where they fall—is best.
Delay cleanup longer than you think. Many beneficial insects don’t emerge until late spring or even summer. If you can, wait until plants are actively growing before disturbing leaf litter or leave them long-term. Most fireflies live underground for 2 years before they emerge!
From Tidy to Thriving
A leaf-covered garden in autumn might look quiet — but beneath that layer is life: cocoons, chrysalises, eggs, and soil microbes preparing to reawaken in their own time. By choosing to “leave the leaves,” you’re not neglecting your garden; you’re nurturing the ecosystem that makes it thrive.
So this fall, skip the leaf blower and grab a mug of tea instead. Let your garden rest — and let life continue quietly beneath the leaves.
