Raking up fallen leaves is often one of the time-consuming chores of autumn, but some experts suggest that homeowners should let them remain on the ground.
Sam Bauer, a turfgrass science expert from the University of Minnesota, suggests simply going over the fallen leaves with a lawnmower from time to time. He recently told the Washington Post: "The leaves have organic matter in them, you're adding good organic matter to your soil when you're not picking them up."
However, there is a certain level of leaf cover that is too much. Bauer writes on a blog post that: "The most important point with [leaf] fall cleanup is that the tree leaves are not covering a significant portion of the turfgrass canopy. 10-20% coverage of your lawn might be okay, but I certainly would make sure the leaves aren't covering any more than that.
"Excessive leaf matter on your lawn going into winter is bad for several reasons. First, it will smother the grass and, if not removed very soon in the spring, it will inhibit growth. Second, it can promote the snow mould diseases. And finally, turf damage from critters (voles, mice) can be more extensive in the spring."