Department of Crop and Soil Sciences - Cooperative Extension

Special Circular 147

Grass cutting is the major time-consuming operation in the maintenance of any turfgrass area. Good mowing practices are perhaps the most important single factor contributing to a well-groomed appearance and the longevity of any turfgrass area.

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Height of Cut

The height at which a given perennial grass can be cut and still survive for extended periods is directly related to its ability to produce enough leaf surface to keep up photosynthetic production of food. Basically this ability is related to the type and habit of growth found in the grass. (The length of internodes, the number of stolons or rhizomes, and the number of basal buds all influence the amount of leaf mass produced by a given grass; hence, its ability to withstand low heights of cut.)

Creeping type plants, such as bentgrass, when properly fertilized and watered are able to produce adequate leaf surface at very low heights of cut. Kentucky bluegrass and fine leaf fescues must be cut relatively high (1½ to 2 inches) because they cannot produce enough leaf mass at low heights to sustain the plants. If bunch type grasses, such as tall fescue or ryegrass, are cut close, too much leaf surface is removed and the plant no longer can carry on enough food making activity to maintain satisfactory growth. Bunch type grasses should be cut 2 to 3 inches in height.

Frequency of Cut

Frequency of mowing is also an important consideration in the maintenance program. Infrequent clipping allows the grass to grow to such a degree that any subsequent clipping removes too much leaf surface. At no time should clipping amounts in excess of ¼ to 1/3 of the total leaf surface be removed at a given mowing. Removal of larger amounts of leaf surface will result in a physiological shock to the plant, cause excessive graying or browning of the leaf tips, and greatly curtail the photosynthetic production of food, thus depleting root reserves. In addition, the accumulation of excessive clippings may smother the grass and provide excellent environmental conditions for disease organisms and insects. Excessive clippings should be removed promptly. Some grasses, especially Merion Kentucky bluegrass and red fescue, produce clippings that are highly resistant to decomposition. To prevent excessively fast build-up of thatch it is recommended that the clippings from normal frequency mowing be removed at least 50 per cent of the time. The frequency of clipping must be governed by the amount of growth. In turf, growth is related to weather conditions, season of the year, soil fertility, moisture conditions, and the natural growth rate of the grasses.

Mowing Practices

It is essential that all types of mowing equipment be kept sharp and in good operating condition. Dull, improperly adjusted equipment not only destroys the aesthetic value of the turf by discoloration and bruising of the leaf tips but also provides more ready access for disease organisms and insects through the damaged leaves.

The proper type of mowing equipment should be used for a given grass under a given set of usage and maintenance conditions. Sharp, properly adjusted reel type mowers are recommended for cutting quality turfgrass areas because they provide a clean even cut and leave the lawn with a well groomed appearance. Reel mowers combined in gang units provide the fastest means of mowing large turfgrass areas. Rotary mowers give a better cutting job if tall weeds and coarse grasses are present. Rotary mowers should be used where grass control rather than appearance is the predominant consideration.

Safety factors should also be taken into consideration in selecting a mower. Due to the nature of the cutting mechanism reel mowers are generally considered safer than rotary mowers. If a rotary mower is to be used it should be of heavy duty construction, well shielded, and have the grass discharge port at the side or front — never at the back of the mower.

Turfgrass areas regularly cut with power mowers sometimes develop a series of wavelike ridges running at right angles to the direction of mowing. The development of this washboard effect may be prevented by regularly changing the direction of mowing (diagonal or right angles). Alternate directions of cut will partially control runners of creeping grass and aid in the prevention of grain and thatch.

Mowing wet grass should be avoided as much as possible. Dry grass cuts more easily, does not ball up and clog the mower, and gives a finer appearing lawn. Timing tests show that mowing dry grass requires less time than mowing wet grass.

Mowing is not a simple operation to be regarded merely as a means of removing excess growth. It is a maintenance practice which has far-reaching effect on the appearance and long life of any turfgrass area.

Mower Safety

Mower and Engine Maintenance

Storing the Mower

John C. Harper, II, Extention Agronomist.

Penn State College of Agricultural Sciences research, extension, and resident education programs are funded in part by Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.

This publication is available from the Publications Distribution Center, the Pennsylvania State University, 112 Agricultural Administration Building, University Park, PA 16802. For information telephone (814) 865-6713.

Where trade names are used, no discrimination is intended and no endorsement by the Pennsylvania State University Cooperative Extension is implied.

Issued in furtherance of Cooperative Extension Work, Acts of Congress May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture and the Pennsylvania Legislature. T. R. Alter, Director of Cooperative Extension, The Pennsylvania State University.

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