By Pam Sherratt and John Street
In addition to leaf area, a direct relationship exists between the height of the turfgrass and the depth and total mass of the root system. Research with Kentucky bluegrass has shown that root growth was more than twice as great when the grass was mowed at a 2.0 inch height verses a 0.75 inch height. In general, turf mowed too short will have a shallow root system with little total root mass. The impact of shallow, weak root systems is most apparent during summer stress periods. When soil moisture becomes limiting, the closely mowed turf usually exhibits stress first and the loss of turfgrass plants is more likely.
Alternatively, mowing sports fields too high can cause some problems, since longer turf shades out new tillers and plants. Turf left to grow too high can also become “clumpy”, especially grasses like perennial ryegrass and tall fescue. Clumpy grasses do not provide an acceptable playing surface from a player safety or performance standpoint. Turf mowed at the lower end of the preferred range will have greater density, which is critical for shear strength and wear tolerance. In addition, close-cut turf provides the athlete with a more true and consistent playing surface.
Standard mowing heights for sports turf grasses are between 1 and 3 inches, depending on the sport and the amount of maintenance the turf receives. Basically, the lower the mowing height, the greater the cultural intensity required to take care of the grass (think micromanaged golf greens versus low-maintenance lawns).
As a rule of thumb, athletic fields that do not receive supplemental irrigation should be mowed at the higher end of the optimum mowing height range. For example, a multi-purpose field with no irrigation should be mowed at 3-inches. Lower mowing heights are employed when the fields are irrigated and when the sport being played relies heavily upon ball:surface interaction. For example, a soccer or field hockey field with an in-ground irrigation system in place could be mowed at 1-1.5 inches.