Mulch mowing is just what it sounds like - chopping leaves into small pieces until it turns into a mulch like material that is returned to the lawn. Leaf debris naturally composts, allowing nutrients to return to the soil. Successfully mulching leaves into the lawn requires frequent mowing in the fall and possibly several passes during one mowing session. It is important to chop leaves adequately until they’re about the size of a dime so the leaf debris breaks down quickly. Specialized mulching mowers are available, and these mower types will also be beneficial year-round to mulch grass leaves into the lawn.
According to K-State Extension, “mowing during the leaf season is not based on grass growth but on the rate at which leaves fall and collect on the lawn. Mow a thin layer, approximately 1” each time. This thin layer is chopped by the mower and then filters through the leaf blades where it works its way down to the soil.” Research has shown that a total of six inches of leaves can be successfully shredded and composted into the lawn and thus returned to the soil without causing damage.
If you determine that your trees deliver more than 6 inches of leaves, it is best to mulch mow then bag. This can be done by first mowing without a bag and then mowing a second time with a bag in place. The second pass will enable leaves to be sucked up into the bag and take-up considerably less space thus allowing you to decrease the volume of leaves two to four-fold. The chopped leaves can be used as mulch for flower gardens and trees to help conserve moisture. Just remember not to use more than 2-3” of mulch around plants and steer clear of the crowns of plants to deter voles and rot. The leftover leaves can also be used in the compost pile.
Another reason to utilize leaves in your landscape, according to the National Wildlife Federation, is that “Removing leaves also eliminates vital wildlife habitat. Critters ranging from turtles and toads to birds, mammals and invertebrates rely on leaf litter for food, shelter and nesting material. Many moth and butterfly caterpillars overwinter in fallen leaves before emerging in spring.”
Leaves should not be dumped into local streams as the extra organic matter can lead to excessive nutrients into our bodies of water thus causing potential algae issues and lower water quality. Leaves that are left on the street can also clog storm drains which can result in flooding.
For questions regarding Warren County Soil and Water Conservation District programs and/or technical assistance on water or soil questions, visit http://warrenswcd.com or call, 513-695-1337.
- Environmental Protection Agency - https://www.epa.gov/facts-and-figures-about-materials-waste-and-recycling/yard-trimmings-material-specific-data
- National Wildlife Federation - https://www.nwf.org/Magazines/National-Wildlife/2015/OctNov/Gardening/Leave-the-Leaves
- K-State Research and Extension, Johnson County - https://www.johnson.k-state.edu/lawn-garden/agent-articles/lawns/mulch-mowing-fall-leaves.html
- Michigan State University - https://www.canr.msu.edu/resources/mulch_leaves_into_turf_for_a_smart_lawn