Summer Mowing Heights for the Home Lawn

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Homelawns: Adjusting summer mowing heights (?), current seedhead production April 30, 2012

We get countless mowing height questions at this time of the year. Mowing at 3" or higher is the best way to maintain a healthy lawn. On a concrete surface, measure from the concrete to the actual blade tip (not the housing). Or simply use the highest setting for most mowers.

Unlike in some earlier recommendations, mow at the same height all year-long. Some adjust the mower higher in the summer months with the hope of improving rooting and thus improving heat and drought tolerance. Raising mowing heights after June 1 is too late because it is after the period of greatest root growth for cool-season grasses. Raising the mowing height at this time does not encourage deeper rooting and thus the plant has to support more leaf material with a proportionally smaller root system. This compromises the plant and will actually require more watering compared to leaving the mowing height at the spring setting. The bottom line is set the mower at 3.0 to 3.5 inches in the spring, and leave it there all year.

Now that Kentucky bluegrass, tall fescue, and perennial ryegrass are producing seedheads, it is especially important to maintain sharp blades sharp. Seedheads detract from the appearance of a turf because they grow quickly and unevenly and the tough seed stalks do not cut cleanly except with the sharpest of mower blades. After mowing, the grass may appear a lighter green to even white because of the frayed seed stalks. The most effective way to control seedheads is through mowing frequently with a sharp mower blade. Do not set the mower lower during seedhead production as some recommend. Seed production only lasts about a month, so the problem should subside quickly. More on seedheads in the lawn can be found here.

Zac Reicher, Professor of Turfgrass Science, zreicher2@unl.edu