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Mow on the highest setting of your lawn mower to promote deep roots, prevent hole damage and crowd out weeds.
Michigan has a tradition of cutting lawns short. Maybe it's because many people want their lawn to look like the fairway of a golf course. Unfortunately, this is not practical for the average homeowner because golf course fairways are mowed three times a week with a regularly ground roller mower and watered daily in the summer. Attempting to mow your lawn at a height of less than 3 inches actually damages your lawn and may require you to apply more insecticides and herbicides.
Increasing the mowing height creates a denser turf that outcompetes weeds. Photo by Rebecca Finneran,MSUExpansion
At what height do you mow?
Determining the actual cutting height of your lawn mower is simple. Pull your mower onto your driveway or sidewalk and measure the distance from the cement surface to the bottom of the blade guard that goes all the way around the path of the blades. Most lawn mowers have an adjustment that allows you to adjust the cutting height between 2 and 4 inches.
What cutting height is best for my lawn?
The highest setting on your lawn mower! The highest setting for most lawn mowers provides a cutting height between 3.25 and 4 inches. This is best for your lawn, but at the 4 inch setting you may sometimes see an "overlay" of grass blades that some people find undesirable. For this reason, some people prefer to cut at 3 or 3.5 inches. For the healthiest and most sustainable approach,Michigan State University Extensionsays 3.5 to 4 inches is most desirable.
Lawns mowed at 1 or 4 inches control weeds, tolerate grass and look just as good as lawns mowed at 2.5 inches.
Why is mowing high good for my lawn?
Cutting height provides five valuable services:
- This makes it much less likely that scalping (grass damage caused by mowing too short) will occur.
- This allows you to cut off about 30 percent of the blade each time you mow (the optimal ratio).
- It promotes the formation of a larger root system that is more resistant to drought.
- It provides broadleaf weed and crabgrass control by shading the soil surface.
- It makes for a caterpillar-tolerant lawn because of its larger root mass.
High weed control means you need to use fewer pesticides on your lawn. If you combine high mowing with modest fertilization (1 to 4 kg of N per year, depending on how green you want your lawn) and watering during dry periods, you may not need to use pesticides - weed killer. or insecticide against caterpillars – on your lawn. If you have not mowed high and watered during dry periods, you may need to do so for at least a year to get a healthy lawn before you stop using pesticides.
Dr. Smithley's work is funded in part byMSU'AgBioResearch.
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Download a printable PDF:Mow high to control weeds and caterpillars
