Mowing Heights

By Thomas Voight, Assistant Professor, University of Illinois Department of Natural Resources and Environmental Sciences

Mowing turf at the appropriate height is important to turf health and appearance. Turf cut too short usually has a shallow root system, lacks density, and often requires pesticide applications to stave off weed and pest infestations that commonly occur in stressed lawns.

From the human perspective, mowing is the most basic and time consuming of all turf maintenance activities. We generally mow turfgrasses for two reasons. The main reason for mowing most turfgrasses is to improve appearance. Mowing turf at appropriate heights and frequencies is a major component of a turf management scheme designed to develop a dense, actively growing, attractive turf. In addition, another reason for mowing turfgrasses is to produce recreational or sports playing surfaces. Activities, such as golf, tennis, lawn bowling, baseball, soccer, and football take place on turf surfaces specifically mowed and managed to accommodate these activities. Conversely, mowing is a destructive practice; it reduces the turfgrass leaf area available for producing necessary plant metabolites and also opens leaves to disease entrance. In addition, when mowed too short, turf can become open, allowing weed invasion (especially annual weeds such as crabgrass or prostrate spurge). Finally, turf mowed too short often has poorly-developed root systems and reduced rhizome spread, which also contributes to the development of a thin, open turf. Thus, for these reasons, it is important to find the balance that produces attractive, healthy turf in an efficient manner.

Mowing Height and Frequency

A neatly trimmed lawn is generally considered to be more attractive than one that is unkempt and shaggy. By mowing frequently and maintaining a uniform turf surface, a neat appearance can be achieved, even at taller heights. Unfortunately, however, a common perception is that a short turf is superior in appearance to tall turf. In reality, turf that is uniform appears neater than uneven turf, regardless of height. Proper height and frequency are the two most important aspects of a turf mowing program.

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Mowing Height

Mowing turf at the appropriate height is important to turf health and appearance. Turf cut too short usually has a shallow root system, lacks density, and often requires pesticide applications to stave off weed and pest infestations that commonly occur in stressed lawns. Conversely, tall turf is often considered to be unattractive because of wide leaf blades, low density, and a clumpy, unkempt appearance. In addition, tall turf may not be satisfactory for some sports applications. When healthy and actively growing, turf can be mowed at the lower heights; raise mowing heights within the desired range during warm-hot periods or when turf is stressed due to drought, disease, shade, insects, or traffic.

The higher the cut, the deeper and larger the root system and a lawn mowed too short will have a shallow root system with little total root mass, a problem during summer stress periods. Closely mowed lawns exhibit stress first when soil moisture becomes limiting. Higher mowing heights during hot weather also keeps soil temperatures cooler, preserving soil moisture. Higher mowing heights also result in fewer weeds per unit area since higher grass provides more shading and competition to the weed seedlings preventing them from becoming established.

Mowing frequency

Turf should be mowed as necessary, not according to a preset schedule. Turfgrasses grow at different rates depending on weather, management, and species. A basic recommendation is to remove no more than one-third of the grass blade at any one mowing. For example, Kentucky bluegrass being maintained at a two-inch height should be mowed when it reaches three inches. This ?EUR??,,????'??one-third rule?EUR??,,????'?? will help maintain maximum turf root growth. Removing more than one-third of the grass blades may cause root growth to cease while the leaves and shoots are regrowing. This practice can be especially destructive if practiced continuously over a period of successive mowings. Roots may not have a chance to fully develop and the plants will thus be more susceptible to environmental and management stresses.

Turf Facts

2 to 3: Inches, the recommended mowing height for most lawns. This slightly higher height screens out light to the soil surface, limiting the germination and establishment of weeds such as crabgrass that need light to germinate.

1/2: Inch. Increasing the mowing height by this amount during the summer can improve the lawn?EUR??,,????'???s ability to tolerate stress.