I have heard that raking to clean up leaves in the fall is no longer a recommended practice, and that it is more sustainable to leave the leaves alone, to decompose in place. Can you provide information supporting this?
This is a complex issue without a single simple answer. Letting leaves lie in place is fine in some situations and not in others. Undisturbed leaves can be a beneficial mulch in the garden, but not all leaves, and not in all circumstances.
Here are a few suggestions:
- Don’t leave diseased or insect-affected leaves on the ground. (As a precaution, I always rake up and remove leaves of fruit trees.)
- Be aware that a thick mat of leaves can make a great hiding place for slugs and snails, and early stages of stink bugs. Learn to recognize their pearly little eggs!
- If you have thick or leathery leaves (such as oak and magnolia), a mulching mower might be a good way of breaking them down to use as mulch.
- If leaves are slippery or are going to obscure uneven terrain that might cause people to trip or fall, rake them.
- If you do decide to collect leaves into a pile, raking is a better method than using a leaf blower (and if you must blow, use an electric or battery-operated blower, which is still noise pollution but at least not air pollution).
In their 2014 book The Living Landscape: Designing for Beauty and Biodiversity in the Home Garden (page 146), Rick Darke and Doug Tallamy do advocate letting leaves lie in the garden, but they recommend running over them with a mower first if you want to have finer material for mulching (so as not to smother fragile plants)—which means they would need to be raked into a mowable pile first. Another way to make leaves more useful as mulch is to compost them for a year—which would also require raking them up and putting them in a pile. Generally, though, the authors favor the let-it-lie philosophy: “In many places, the most conserving, functional, low-maintenance approach to autumn leaves is to let them lie where they fall. This is exactly what happens in unmanaged forest ecosystems. Though a too-heavy leaf layer can have a negative effect on delicate herbaceous plants, most trees and shrubs and a wide range of sturdy perennial herbs grow well under natural leaf fall.”
I will point out that a tiny urban garden is quite different from an unmanaged forest ecosystem, so sometimes we need to rake leaves where they impede access to paths, steps, sidewalks, etc. And again, consideration should be given to preventive measures. Don’t let lie the leaves of any plant you know to be struggling with pests and diseases.