Is there a sound reason behind raking leaves pertaining to lawn health, or is it simply an aesthetic choice?
You’ve probably heard that lawns, too, have to "breathe," and that they can be smothered if a thick layer of unshredded leaves is left on top of them over the winter, causing problems such as snow mold. That is true, but it is only part of the reason why we rake lawns.
Most lawns in the Northern U.S. are composed of one or more cool-season grasses. "Cool-season" lawn grasses are so called because they're most active during those periods of the year when moderately cool weather predominates. Fall is one of those times. Blessed with sufficient sunlight, nutrients and water, and enjoying temperatures that are neither too cold nor too hot, cool-season grasses such as Kentucky bluegrass revitalize themselves in fall. This is when they must "make hay," strengthening their root systems.
But a thick layer of fallen leaves can impede the growth of these grasses. Why? Because they can deprive the grass of one of the key elements I mentioned: sunlight. If not raked up in time, a thick and/or matted layer of fallen leaves casts excessive shade over the grass below. You don't have to rake up every last leaf; a shortcut is to mow, so as to shred left-over leaves.