Years ago we could rake a pile of leaves and burn them in the corner of the yard. The unforgettable autumn aroma of burning leaves made the raking labor all worthwhile. But in-town burning is heavily frowned upon nowadays, easily inviting a visit from the authorities. And for good reason. That means modern day raking involves stuffing all those leaves inside bags, or waiting for the wind to blow them in the direction of a neighbor who enjoys yardwork.
Leaves can be added to the compost bin, or used as protective mulch around roses and other perennials. Or they can just be mowed over.
What about just mowing over the leaves? Is the practice good, bad, or indifferent to the lawn?
Michigan State University wanted a research-based answer to the leaf-mowing question, so did an extensive 3-year study. They mowed leaves spread thicker than most of us encounter, such as 6 and 12 inches thick over the lawn. They used a homeowner type of push mower, with the exit covered, so the leaves pulverized better, rather than being shot out sideways.
Here’s their results:
- In summary, mowing leaves into the lawn proved very beneficial for lawn health. Lawns with mowed leaves were healthier than lawns from which the leaves were removed.
- The study proved that pulverized leaves added nutrients, aided in lawn moisture retention and helped control weeds.
- After 3 years of mowing leaves into the turf, there was nearly a 100% reduction in dandelions and crabgrass.
Researcher at Michigan State offered the following:
“Research clearly indicates that the practice of mulching leaf litter into existing turf grass canopies provides benefits for the soil and the turf grass plant. It is important to use a rotary mower that pulverizes the leaves well and that the leaves are dry when mowed. A mulching mower works best, or a normal mower with a covering over the discharge opening (usually standard with most mowers sold today) works well also. Sharpening the mower blades and a slow movement with the mower will help to grind the leaves finer. It may be necessary to make as many as 3 or 4 passes over the area to grind the leaves fine enough, especially if you haven’t been mowing regularly. It is best if the leaves are mowed regularly, not allowing them to lie on the turf more than 3 or 4 days.The pulverized leaves will settle into the turf within a day or two, particularly if followed by rain. Take care that the pulverized leaves do not cover the grass blades entirely. Fall is a very important time for the turf to photosynthesize and store carbohydrates.”