Highs and mows: the impact of proper lawn mowing height
Mowing your lawn to the correct height can keep your yard green, healthy and long-lasting.Posted — Updated
While you think the shortest possible trim on your lawn will save you the time and stress of frequent mowing sessions, improper grass height can spell trouble for your lawn.
You don't have to get out a measuring stick and check your lawn height each time you mow, but following a few general rules of thumb can help keep your yard green and clean.
The proper grass height isn't one-size-fits-all, so you'll need to investigate what type of grass plant is in your lawn.
"The correct mowing height for cool season grasses such as tall fescue, ranges from 2.5 to 3.5 inches," said Grady Miller, professor and extension turf specialist in the Crop & Soil Science Department at North Carolina State University. "For most warm season grasses such as Zoysia and Bermuda, they are best mowed at a range of .75 to 2 inches."
An easy way to follow these measurement suggestions is to never cut more than one-third of the height from the stem to the tip of a grass blade. To simplify the process, find out what the ideal height of your yard’s grass should be, then let it grow one third longer than that height before you mow next.
Mowing at the correct height for your grass is actually one of the easiest and most economical ways to combat weeds. Unfortunately, some lawn enthusiasts mow their lawns shorter than recommended. That close mowing may cause scalping — or mowing so low that it exposes the stems of grass blades which induces stress, making the grass plant less able to compete with crabgrass and other weed species.
Another issue with mowing your lawn too short is that grass blades, necessary for photosynthesis, are reduced so much that not enough food is manufactured to meet the requirements for healthy grass plants, especially the roots. The result is a weak, thin lawn unable to ward off pest and environmental stress.
A healthy, dense, vigorous lawn is better able to out-compete weeds. In a scalped lawn, weeds can quickly dominate. This was demonstrated at the Lake Wheeler Turfgrass Field Lab in Raleigh, where tall fescue was maintained under four different mowing heights: one, two, three and four inches. After one to two years, crabgrass populations increased as the mowing height was reduced.
The experiment measured crabgrass coverage at one inch, two inches, three inches and four inches, and results of crabgrass incidence to those respective mowing heights were: 95%, 48%, 13% and 0%.
Depending on the type of grass you have, the proper care methods will vary by season — although all grasses should be left to grow taller in summer and during droughts. For warm-season grasses, cut your lawn shorter in the spring in order to get rid of any dead grass blades left from the winter. For cool-season grasses, a shorter final mow in the fall can help prevent snow buildup from causing spots of mold.
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