How high to mow grass
The one-third rule, from university extension guides.
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The one-third rule
K-State says to remove no more than one-third of the grass blade at any one mowing. Maryland Extension gives an example: to keep a 3-inch lawn, mow when the grass reaches 4 inches.
Why it matters
K-State says removing more than one-third of the blades may cause root growth to stop while the leaves regrow, leaving plants more open to stress.
Height depends on the grass
Maryland Extension lists different mowing heights for different grass types. University of Minnesota Extension says to keep a typical residential Midwest lawn at 3 inches or higher. Your local extension office can tell you the height for your grass.
If it got too tall
K-State says to bring tall grass down in steps, using the one-third rule each time, with several days between mowings.
Mow dry grass
K-State says wet turf may clog the mower or form clumps on the lawn. The CPSC also says not to cut the grass when it is wet.
FAQ
General information only. Read the operator's manual before you mow. Keep children and pets indoors or well away from the area you mow, and never let a child ride on a mower as a passenger. The American Academy of Pediatrics says that, in general, children should be at least 12 years old to operate a walk-behind power mower safely and at least 16 to operate a riding mower safely. Before you clear, adjust, or service the blade area, turn the mower off, wait for the blade to stop, and disconnect the spark plug wire; on a battery or corded electric mower, follow the manual to disconnect its power. Refuel outdoors, only with the engine off and cool. Wear sturdy closed-toe shoes and eye and hearing protection. In an emergency, call 911.
Next: grass clippings
Grasscycling, explained.
