That pile of fallen leaves isn't yard waste — it's a winter shelter for hundreds of species that call Edmonton home. Leave your leaves, and give them a home for the winter.
Delay yard cleanup until average temperatures reach above 10 °C.
Below this temperature, many beneficial pollinators like native bees, butterflies and moths remain dormant inside leaf litter. Raking or blowing leaves and yard debris away before they emerge can destroy their shelter and the entire food web that depends on them.
Leaf litter isn't dead — it's one of the most biodiverse microhabitats in urban and suburban yards.
Around 70% of Alberta's 375 native bee species nest in the ground. Their nest entrances are insulated by fallen leaves through freeze-thaw cycles all winter. Without this cover, eggs, larvae, and dormant queens don't make it to spring.
Alberta Native Bee Council • Xerces SocietyRemoving leaf litter cuts butterfly and moth species richness by 40% and abundance by 45% in a single season. Swallowtails, and fritillaries all overwinter as eggs, caterpillars, or chrysalises tucked in dead leaves.
Ferlauto & Burghardt, Science of the Total Environment, 2025Leaf removal reduces beetle populations by 24% and spider populations by up to 67%. Ground beetles eat their own weight in pests — aphids, slugs, grubs — every day. Removing their winter home means more pest pressure next summer.
Ferlauto & Burghardt, 2025 • Xerces Society96% of terrestrial bird chicks are raised almost exclusively on caterpillars and insects. Ground-feeding birds like chickadees, sparrows, and robins forage through leaf litter all winter for hibernating insects, larvae, seeds, and earthworms.
Douglas Tallamy, University of Delaware • Audubon SocietyYards where leaves are left to decompose hold 32% more soil carbon. Fallen leaves return 50–80% of the nutrients trees drew from the soil — nitrogen, phosphorus, potassium, and more — all for free, better than most fertilizers.
Ferlauto, Burghardt & Schmitt, Plants, People, Planet, 2024A layer of leaf litter reduces surface water runoff by 29–31% and soil erosion by up to 85%, keeping moisture in the ground rather than flowing into storm drains. It also suppresses weeds naturally — no herbicides needed.
PLoS ONE, 2014 • Rutgers NJAESBest and easiest: just leave your leaves where they lie in fall. But if that doesn't work for you, there are other options
Move leaves off your lawn onto garden beds and around trees. A few inches of leaf cover is perfect — deep enough to insulate, shallow enough to let water through.
Can't move them? Run your mower over dry leaves to shred them. The small pieces decompose quickly without smothering grass, returning nutrients directly to your lawn.
Even a small undisturbed pile in a corner of your yard makes a meaningful difference. Bumblebee queens and ground beetles aren't fussy — a sheltered spot is enough.
The most important step. Before tidying up in spring, check the forecast. Wait until daily temperatures are consistently above 10 °C — that's when it's safe for insects to emerge.
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