Fall foliage along Highway 2 in Michigan’s Upper Peninsula Image: Todd Marsee, Michigan Sea Grant
By Reese Carlson
As the leaves blanket the ground in stunning shades of reds, yellows, and oranges, experts say to think twice before bagging them up.
That said, perhaps your neighbor with the meticulous lawn may disagree.
“The leaves contain nutrients and they also are a source of organic matter,” said Susan Barton, a professor of plant and soil sciences at the University of Delaware. “So, if you allow the leaves to go back into the landscape, you are providing nutrients for plants to take up and you are providing organic matter that will improve the soil structure.”
The leaves cannot be left piled on the grass, Barton warned. That prevents photosynthesis and smothers the grass.
“When the leaves fall on a lawn, we have to rake them up off of the lawn or chop them up with a lawn mower so that they are finer and can sift down in through the grass blades,” Barton said. “If we have a layer of leaves on the lawn it will exclude light and that would be detrimental to the lawn.”
Fallen leaves can also be used as a natural fertilizer for garden beds, said Trey Rogers, a professor of plant, soil, and microbial sciences at Michigan State University.
“Grind those leaves right up,” Rogers said. “And they can be a wonderful, wonderful fertilizer that doesn’t cost you anything.”
And a healthier lawn means fewer weeds, Rogers said.
A 2022 Purdue University study published in the Urban Agriculture & Regional Food Systems Journal shows that leaf waste used as fertilizer in garden beds with tomato plants greatly increased concentrations of soil organic matter. More organic matter means healthier soil for growing plants.
Another environmental plus: when bagged up leaves are taken to a landfill, they are not able to naturally decompose. Instead, they take up space.
“The leaves are really a great resource when we allow them to be recycled into our landscape,” Barton said. “So, you’re taking what could be a resource and making it a problem that’s filling up the landfill.”
About those meticulous neighbors?
There are ways to limit how much of your leaves blow into neighboring yards, Barton said.
“Chopping up the leaves will dramatically reduce the blowing of the leaves,” Barton said. The easiest leaf chopping method is to use a lawn mower.
Wetting leaves prevents them from blowing out of the yard and might even allow for the leaves to break down faster into your lawn or garden bed, Rogers said.
Regardless, he figures hanging onto the leaves is well worth it:
“Free fertilizer and less time spent weeding? I’m all in.”