This past fall there was a lot of talk about “leaving leaves” in the garden not only in gardening media circles, but in mainstream media too. Any advice that advocates skipping yard chores is sure to go viral, but let’s take a closer look so that you understand exactly where and why this is not bad advice, and where it’s a terrible idea.
The National Wildlife Association’s blog post was written a year ago, but went viral this fall. The advice, while not actually wrong, was a little unclear.
Yes, leaving fallen leaves to decompose does return valuable nutrients to the soil, provides habitat for lots of important and valuable insect species over winter, and acts as a natural mulch. Unfortunately, the article was not exceedingly clear about one place you do NOT want to just leave your leaves: your lawn.
The only way to leave the leaves on your lawn is to chop them finely with a mulching mower or a leaf shredder, or shred them in a trash can with a string trimmer, then return them to the lawn. (We describe how to do that in this newsletter article that we also wrote a year ago that didn’t go viral…oh well) You cannot leave a layer of fallen leaves as-is on your lawn…unless you want to have to do a lot of lawn repair next year. Layers of leaves block sunlight and trap excess moisture against the lawn, resulting in bare patches come spring.
It’s also a good idea to keep layers of leaves off of beds of fall- and winter-interest plantings like pansies for the same reason. A thick layer blocks sun and risks disease in wet weather. Rule of thumb: if you can’t see the plants underneath, the leaves are probably going to cause a problem.
Yet there are plenty of places where you can leave the leaves. You can leave leaves in wooded areas, on mulched areas, under shrubs and around perennials as long as you think of them like mulch: not built up too thickly (3-4” at most” and not piled up against stems and trunks. (You should probably think twice about thick layers of leaves if you have vole problems-voles can burrow under the leaves and wreak havoc in your garden over the winter.)
The main argument for removing leaves from everywhere but the lawn is purely aesthetic-most people prefer the clean look of traditional mulches. But leaving leaves and mulching over top of them in spring is an acceptable and ecologically safe option.