Mower blade sharpening, explained
Why a sharp blade matters, and who should do the job.
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Why sharp matters
K-State says dull blades tear turf and leave a ragged look, and that water loss and turf disease can be greater from ragged leaf edges. UMN says cleanly cut grass blades are able to conserve water.
How often
Maryland Extension says to sharpen mower blades at the beginning of each mowing season or replace them once a year. It gives a rule of thumb of sharpening after about 10 cumulative hours of use.
Signs of a dull blade
Maryland Extension says dull blades give cut grass a frayed and brown-tipped look.
Who should do it
We do not give sharpening steps. AAOS says hands and feet should never be used to touch the lawn mower blade under any circumstances, even if the engine is off. The maker's manual sets how a blade is removed, sharpened, balanced, and replaced. If the manual sends you to a dealer or service shop, or you are not sure, use one. K-State says reel mowers usually require professional adjustment and sharpening.
Before anyone works near the blade
Ohio State says to shut off the engine and disconnect the spark plug wire before maintenance, and warns that blades may continue to spin after the engine has been shut off. The AAP says blade settings should be done by an adult, with the mower off and the spark plug removed or disconnected.
Never clear it by hand
AAOS says to use a stick or broom handle, not your hands or feet, to remove debris in lawnmowers.
Sources: Kansas State University, Mowing; University of Minnesota Extension, Mowing practices for healthy lawns; University of Maryland Extension, Maintaining an Established Lawn; Ohio State University Extension, Power Lawn Mowers; American Academy of Pediatrics, HealthyChildren.org, Lawn Mower Safety: Information for Families; AAOS OrthoInfo, Lawn Mower Safety.
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: maintenance basics
Oil, plug, filter, manual.
