The Golden Rule of Mowing
If there were just one rule to follow for mowing your grass, it would be this: cut no more than 1/3 of the grass blade at one time.
If you want to keep things simple and easy to remember, you can stick to this simple rule of thumb: try not to remove more than one-third of the leaf tissue present in a single mowing. Here’s what the experts have to say about it:
“The lower you go, the more frequently you have to mow to maintain the desired height without taking off more than one-third of the plant,” says Peter Landschoot, Penn State turfgrass specialist. He notes a shorter lawn also often has more weed problems because the canopy isn’t as thick. The open canopy allows more light to reach the soil and germinate weed seeds.
If lawns are continually allowed to grow too long and then cut back dramatically, it can stress the grass. Stress will cause the grass to pull nutrients from the root system, degrading the roots and eventually resulting in a thinning, unhealthy lawn, says Clint Waltz, University of Georgia extension turfgrass specialist.