See our chart under, "Planting Rates" for recommended mowing heights of your lawn. Most mowers have adjustments for raising and lowering the mowing height. Be sure to set your mower on a solid surface such as a driveway or sidewalk and determine what height you get from various settings. Then, set your mower’s cutting height to match the appropriate height of cut for your particular grass. If your lawn has a white hue rather than a green color after you mow, it is a good bet that you are cutting too low. While there are some differences in tolerable cutting heights between the various species of warm and cool-season turfgrasses, a general rule of thumb is to clip them in the 2-3 inch range. For cool-season turfgrasses, it is always a safer bet to begin raising their cutting heights in late spring/early summer to maximize tolerance to environmental and pest pressure. Taller cutting heights at these times help maintain the plant’s root system. On the other hand, warm-season grasses respond to mowing on the lower side of their recommended range in the summer by increasing in density. Note that shorter mowing heights will require more frequent mowing.
The quickest way to improve lawn quality AND turf health is to clip it with a sharp blade, and a sharp blade will also improve fuel-use efficiency and extend engine life. When is the last time you sharpened and balanced your mower blade? Homeowners should sharpen the blade at least twice per growing season: start the year off with a sharp blade and sharpen it again in the summer.
Perhaps you have also heard of something called the “1/3rd rule” of mowing -- that is, never remove more than 1/3rd of the leaf blade at any mowing event. Removing most of the foliage in a cutting event shocks the plant, forcing it to redirect its food resources from roots and stems towards new leaves. If the turf has gotten away from you, resist the temptation to scalp it in a single mowing event. Instead, slowly drop the mowing height every 2-3 days while returning the turf to its ideal cutting height range. This approach takes a little patience, but it will maintain plant health and prevent you from having unsightly piles of clippings that not only look bad, but can also shade and heat the turf below.
Finally, return clippings as often as possible to your turf. Clippings are nothing more than organic fertilizer for your lawn, and if you follow the 1/3rd rule, you will never produce enough clippings to cause problems with your lawn. Many rotary mowers are already outfitted with mulching attachments that chop the clippings into even finer pieces that are broken down by the soil’s microbes that much faster. You can reduce your turf’s fertility needs and help the environment by keeping your clippings in your lawn.