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Many butterfly and moth species, along with other creatures, overwinter in fallen leaves, so leaving those leaves on the ground can help them survive and prosper.

Recent research says that a longtime gardening tradition — the big fall clean-up — may do more harm than good. In many ways, letting existing natural systems do what they have always done is better for your soil, your garden, your back and the environment.

Like many things we do in the garden, a fall clean-up is for aesthetic reasons — not because it’s good for plants or the garden. Many gardening practices sound like they make sense but are not shown by research to be beneficial.

Cleaning up is not a natural process. When leaves fall from the trees, they create the best mulch you can’t buy. This insulates the tree roots from cold or heat. They are an excellent fertilizer, full of micronutrients. Fallen leaves are one of many ways to build beautiful soil — especially important for those of us living in new developments where the existing topsoil was scraped away to build our houses. Those leaves break down and are incorporated into the soil by earthworms and other detrivores (an animal that eats detritus), and soil microorganisms.

There is one caveat, however — they can smother a lawn if they are too thick. So, on the lawn, run your mower over them a few times, rather than raking or blowing them; the fine leaf bits will settle in between the grass blades, and quickly decompose, improving the soil there. No noisy leaf blowers, greener grass! Win-win!

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Leaving those leaves on the ground can help build rich soil, and spare a gardener's back during the traditional fall yard clean-up.

Did you know that, unlike monarch butterflies, most butterflies and moths don’t migrate? They overwinter here as eggs, or larvae, and many do that in leaf litter. Wooly-bears snuggle into dried leaves, as do fritillaries, swallowtails and luna moths. Queen bumblebees burrow into the top inch of soil and need that leaf blanket to shelter them. Many lizards and other insect-eaters also need the protection of leaves.

Besides leaves, other plant parts are equally important to the critters around us in winter: small birds love coneflower, black-eyed Susan or sunflower seedheads, so you don’t need to cut them down until spring. Their seeds are high in nutritious fats and nutrients. Many animals and birds use dried ornamental grass blades for shelter or nesting material. Many native bees need ornamental grass to lay their eggs.

If you live in an HOA with strict regulations, you can still garden for wildlife and the environment. As mentioned, mow the leaves into the lawn, or ask your landscaper to — a green, tidy lawn will go a long way toward appeasing the powers that be and keeping your yard looking tidy. Keep the most visible areas of your yard mulched with hardwood mulch, with your perennials cut back and shrubs tidied up. Make the wilder areas in the back, behind taller perennials, or behind a shed. Just leaving one wild area is a huge benefit — try having one this fall!