Leaving the leaves

Last fall I departed from past practices and let fallen leaves lie on all my garden beds through the winter. The reason for the change was a new recognition that this would help native insects make it through to spring. As the weather warms and daytime temperatures stay moderate, I’m having the first opportunity to assess how this worked out.

Bloodroot emerging from last fall's leaves

    Years ago, I tried using whole leaves as mulch to improve soil in the front yard. I soon recognized that this was an un-neighborly act, because the leaves blew off our property and ended up on other people’s carefully raked lawns. This blunder led to the purchase of a leaf shredder. Shredded leaves stay put. I used them as mulch for about 20 years. 

Shredded leaves make nice mulch and don't blow around

    Then I learned that by chopping up the leaves, I was probably also chopping up desirable insects. Some dormant adult insects spend the winter hiding among the leaves, and others lay their eggs there. If I let the whole leaves lie through the winter, the eggs could hatch and adult insects could emerge when the weather warms in spring. 

Beneficial lacewings can winter in leaf litter

Those emerging insects would contribute to a healthy balance of insect populations in the garden. That’s why last year I not only let leaves that fell on the backyard beds lie un-shredded. I also dragged in as many leaves as possible from my block and a neighbor’s lawn. All those brown leaves are now lying on my garden.

    I’m still working out this system. My approach this spring is to rake the top layer of fall leaves gently off perennial beds. New shoots from the perennials don’t seem to be able to reach the sunlight through mats of undecomposed whole leaves. I see new growth heaving up a section of leaf mulch, and I can’t resist lifting the leaves off to uncover the emerging yellow-green stalks. 

I peeled away the top layer of leaves to uncover emerging perennials

This may be a remnant of an old way of thinking. Maybe next year I’ll have learned that even this careful raking isn’t necessary.

    Around trees and shrub, though, the whole leaves seem to be doing nothing but good. Like wood chips, they’re keeping the soil steadily cool and moist. They seem to be suppressing weeds too, like any good mulch. 

No need to rake away fall leaves that surround trees and shrubs

Tough, leathery leaves from our neighborhood’s red oaks decompose slowly. Even so, they’ll eventually break down and add organic matter to the soil. Like my sheet mulching project, this is essentially a way to let compost happen with less intervention. Instead of moving leaves to the compost pile and then carting them back to the beds after they decompose, I’m letting soil organisms do the work where the leaves fall. Imitating natural processes is a lot less work!

    I do need to move some of those leaves to the compost piles, though, because the bins are pretty depleted. I’ll need some compost to make homemade potting mix. No worries—there are plenty of leaves to spare.

Leaves will help make compost for peat-free potting mix