Mowing Too Early Can Destroy Your Lawn—Experts Warn

Timing your first mow of the season is key to getting the most out of it. Mow too early and you’ll damage grass that’s still lying dormant. Mow too late and you could shock your grass by taking off too much at one time. Soil temperature, grass height, and where you live can all help you determine when it’s time to crank up your mower for the first time this year. We sought help from Steven Corcoran, CEO of Lawn Love, for guidance on when and how to make that first mow of the season. 

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Soil Temperature

Air temperature impacts when grass will start growing, but soil temperature is a better indicator. “Look for cool-season grass soil temperature to be between 45°F-55°F, or 60°F-65°F for warm-season grass,” Corcoran says. You can check the status of your lawn using a soil thermometer, which you can find for $10, or use a meat thermometer. Insert the thermometer 2 to 4 inches in the ground in the middle of the day and leave it there for 3 to 5 minutes to get an accurate reading. 

Be patient and wait for your grass to wake up before mowing it, Corcoran says. “You should never mow when your grass is still dormant, or even partially dormant,” he says. “This can disrupt its growing pattern and damage the grass.” 

Grass Height

While soil temperature can clue you in to when your grass is waking up, the best way to time when you make your first mow is grass height, according to Corcoran. “What I recommend is waiting until your grass blades are 4 inches tall, as that is usually enough of an indicator that everything is active and ready,” he says.  "For warm season grass, make your first mow when the grass reaches 1.5 to 2 inches tall."

Region

You shouldn't use a calendar to determine when you make your first mow. Winters can vary in severity from year to year and hence alter when grass starts growing by weeks from year to year. Still, a calendar that’s based on your region can give you an idea of when to start paying attention to your lawn. 

 “The timing depends a ton on where you live – usually in southern regions you can expect it to be around mid-March whereas in northern regions it can be anytime from late-March to late-April,” says Corcoran. 

Since grass begins growing when daytime temperatures stay consistently around 50°F to 60°F, the time to mow can vary significantly from region to region.