It’s the bad gardening advice that will not die. Why? Because it sounds so great, so freeing, so right. What? I don’t have to rake anymore? I can leave the leaves that fell all over my lawn and flower beds exactly where they are? What’s wrong with that? That’s awesome!
Actually, this is fine forest management advice. On the forest floor, leaves drop and gradually decay, the operative word being gradually. Nobody rakes them or has to. In urban and suburban neighborhoods, it’s not quite the same. For example, on my street, the area in front of my house, including the sidewalk and neighboring driveways, is now inches deep in thick Norway maple leaves (with some other maples mixed in). We have dense tree cover for a city street. The leaves on the hardscaping are not going to do anything except maybe end up in the storm drains, where they’ll clog things up and add some extra algal content to our rivers and lakes for good measure. Obviously, they are not adding organic benefit to the sidewalk.
Then there are the leaves completely covering my front perennial beds. If left, they will simply remain, a heavy, sodden mat. Time to decay? Maybe a couple years. I’ve never seen it. They’ll block oxygen from the soil, and, if I had a lawn, they would do their best to smother it. As it is, if I left them, in the spring I would have bulbs struggling up, each green spike surrounded by a creepy brown collar, with pale green perennial shoots crushed underneath, unseen. Not really what we’re aiming for with a garden.
There are good ways to deal with leaves that, sadly, are not mentioned in these science-free, commonsense-horticulture-free posts from well-meaning wildlife organizations. Yes, leaves can be left to mulch perennial beds, but leaves like mine should be shredded first. For lawns, a mulching mower will break up the leaves, allowing them to benefit plants and soil. Unfortunately, the National Wildlife Federation link (from 2014) mentioned above does not bother to mention any of these strategies. (I do agree with not cutting back perennials or clearing beds as part of a “fall clean-up” effort.) By the way, where I live, the city picks up bagged leaves and takes them to a composting operation.
I was hesitant to harp on this yet again. Susan already has, and so have I. And I wouldn’t have done it this year if an enewsletter I otherwise trust for good links and info had not included the NWF’s misguided leaf post as its first link this week. And members of my facebook gardening group are also posting it. So once more into the fray we go. There is science to back the case that heavy leaf cover harms soil and plants, but you don’t even need to read it. Leave a heavy blanket of leaves on your lawn without shredding them or mowing over them and see what happens.
When it comes to the natural environment, most of my friends are on the “science first!” bandwagon, as am I. But too many of them stop short of horticultural science.