I may be one of the few folks that enjoy mowing the lawn. Mowing is perhaps the most common cultural practice performed in most landscapes. When performed properly, mowing is used to maintain a particular turfgrass height and appearance that supports a specific use and aesthetic. It is important to remember that while turfgrasses evolved to tolerate mowing, this practice is still a stress that has the potential to compromise overall turfgrass health and vigor. Therefore, it is important to take steps to adopt appropriate mowing practices that support the health of the grass.
Two factors determine the appropriate height of cut for any lawn: the species of grass and the use of the area. A general guideline for mowing heights here is 2 inches for bermudagrass, centipede, and zoysia, and 3 inches for St. Augustine. It is important not to mow too low as taller blades produce more food and deeper roots which in turn leads to more drought tolerance, more shade tolerance, more wear tolerance, less erosion, and better water infiltration.
As a rule of thumb, no more than 1/3 of the grass should be removed at any one time. For example, if your intended mowing height is 2”, then you would need to mow before the blades exceed 3” in order not to “scalp” the turf. Appropriate mowing frequency is determined by the rate of growth. Several factors, including temperature, precipitation, light, and nutrient management impact the rate of turfgrass growth throughout the year. Remember that supplemental nitrogen (N), though generally beneficial to turfgrass growth, will encourage faster growth that may not be appropriate for areas that will be mowed less frequently. Nitrogen applications should, therefore, be partially determined by management capabilities and even cost this year due to sky high prices. During peak periods of growth for warm-season grasses, more frequent mowing (sometimes twice a week) may be required to prevent turfgrass scalping. Scalping is the excessive removal of leaf growth from lawns resulting in injury to the grass. It is important to remember that plants require adequate leaf tissue for photosynthesis and energy production (all leaves are solar panels after all). Excessive removal of leaf tissue through scalping can be detrimental to turfgrass health, as it limits the plant’s ability to produce adequate energy to sustain growth. When turfgrass is mowed too infrequently, scalping is more likely to occur. When lawns become unavoidably overgrown, consider gradually lowering the height of the grass over time to prevent the removal of more than 1/3 total height in a single mowing.
It is beneficial to mulch or recycle turfgrass clippings generated from mowing. Turfgrass clippings are generally 2-4 percent nitrogen and, when recycled back into the lawn, can reduce the need for supplemental nitrogen fertilizer by up to half. Mowed clippings should be evenly dispersed across a lawn. Avoid creating rows or piles of clippings, as this can damage underlying turf by restricting sunlight and water. Also, remember to always keep lawn mower blades sharp to avoid “split ends” and a discolored turf. I got a new blade last weekend!
For more information, see “Mowing Recommendations for Warm-Season Grasses” under publications on the Aggie Turf website (aggieturf.tamu.edu).
Greg Grant is the Smith County horticulturist for the Texas A&M AgriLife Extension Service. He is author of Texas Fruit and Vegetable Gardening, Heirloom Gardening in the South, and The Rose Rustlers. You can read his “Greg’s Ramblings” blog at arborgate.com, read his “In Greg’s Garden” in each issue of Texas Gardener magazine (texasgardener.com), and follow him on Facebook at “Greg Grant Gardens.” More science-based lawn and gardening information from the Texas A&M AgriLife Extension Service can be found at aggieturf.tamu.edu and aggie-horticulture.tamu.edu.