It’s Autumn and the leaves are falling.  Traditionally we raked them to gather them into piles and perhaps put them in bags to be carted away with the other trash.  Or maybe we used a power leaf blower and added diesel or particulate matter pollution to the air as well as noise.  But practices are changing, and those leaves are an essential resource for your garden ecosystems, so don’t throw them away!  Leave the leaves!

Consider mulching the leaves – chopping them into small pieces with a lawnmower or a leaf shredder and leaving the mulched pieces on your grass lawns or adding the mulch to your flower beds. The benefits of leaf mulching are numerous:  it enhances the health of your yard by creating valuable compost, which enriches the topsoil.  Mulching improves soil structure, reduces the need for fertilizer, and avoids water pollution by reducing phosphorus and fertilizer leaching.  By adding organic matter to the soil, leaf mulching improves water retention and percolation for improved rainwater management.  Additional organic matter loosens the soil, allowing grass roots to penetrate more deeply, improving grass health. Mulch, when spread on garden beds, suppresses weeds and improves soil quality; when it decomposes into compost, it suppresses disease.  And you will save money instead of having to buy mulch in bags from the store.

Don’t chop all the leaves.  Let the insects live!  Mulch the leaves on the lawn to avoid smothering the lawn – but rake whole, unchopped leaves around the base of trees and shrubs, under tree canopies, or into perennial beds.  Not only will they protect the roots of these plants and enrich the soil, but they are an important habitat for overwintering beneficial insects, including butterflies, whose cocoons lay in the leaves.  You will encourage biodiversity in your yard and help insect populations, which are in serious decline.  Ideally these leaves should not be cleaned  up at all in the spring, but if you want to give in to that impulse to “spring clean” your garden, wait until there have been several 50-plus degree days in the spring so insects can emerge.  And you may find that by spring the leaves have decomposed, adding to the health of your soil.

Pile the leaves for compost. If you prefer the neat look, pile the leaves where they are out of the way, maybe in the woods.  Leave them alone where they won’t be disturbed, best where they are not too sheltered, as the pile needs to get wet occasionally.  After about two years or less, you’ll have compost ready to add to your flower beds -- a rich and crumbly blend of partially decomposed organic material that will utilize microorganisms to break down and decompose organic matter.  This compost provides a balanced source of plant nutrients and improves your soil’s texture, water-holding capacity, and fertility. Establishing and maintaining a compost pile is the easiest way to produce the best possible food for your garden.  IMPORTANT: Chester County does not allow one to use food scraps in a compost pile, unless you have a closed compost bin that will block odors that could attract pests such as rodents and flies. Your homeowners association may also have restrictions.

Reference:  http://www.leaveleavesalone.org/, part of the Healthy Yards Campaign.

And Leave the Stems, Too.  Native bees are important pollinators, and they are declining like other insects under environmental stresses.  The survival of wild bees depends, among other things, on finding a suitable nesting site.  Many wild bees gnaw their nest tunnels into the marrow of plant stems, and they prefer vertical stems.  By not leaving your garden "broom-clean" for winter in your autumn garden care you can leave an important habitat for some wild bee species.  Leave those dead plant stems through the winter – and into spring to allow the wild bees to hatch out.  If you need to clean away the stems, tie them in a vertical bunch and put them in an out of the way place in your garden – treat them as an ornament!