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Mowing Turfgrasses

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.

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

  • Know the proper way to start and operate the mower.
  • Do not permit children or others unfamiliar with the mower to operate it.
  • Know how to stop the engine quickly.
  • Never leave the mower running and unattended.
  • Do not permit a self-propelled mower to pull you. Set a pace where you have control of the mower.
  • Do not attempt to adjust or clean the mower when it is running
  • Do not refuel a gasoline engine while it is running.
  • Do not attempt to clean or adjust a mower too quickly after shutting it off. Blades may continue whirling, and the engine will be hot enough to cause severe burns.
  • Never attempt to work on a mower until the spark plug is disconnected.
  • Keep hands and feet away from all mowing parts.

Mower and Engine Maintenance

  • Each mower is supplied with an Owner's or Operator's Manual by the manufacturer. This manual tells how to operate and care for the mower and the engine.
  • Regardless of the mower type the blades should be kept sharp at all times.
  • On reel type mowers regularly check the reel blade to bedknife adjustment. On rotary mowers keep all blade bolts tight and use a blade that is properly balanced.
  • Keep all height of cut adjustments tight.
  • A clean engine is easier and safer to work on. Clean the engine each time it is used.
  • Engines need clean air. Check the air cleaner frequently, especially if the mower is used under dusty conditions.
  • Keep the correct type and amount of oil in four cycle engines. Use quality oil from a reliable company. Change oil in accordance with the Operator's Manual instructions.
  • Use the proper oil-fuel mixture in two cycle engines.
  • Spark plugs should be cleaned and gap reset every 100 hours of operation. If the porcelain insulator is cracked or the plug badly burned, it should be replaced.
  • Keep spark plug cable clean and free of oil to prevent "shorting out." Connections on each end of the cable must be kept tight.

Storing the Mower

  • Clean mower and engine thoroughly.
  • Drain or run out all gasoline from carburetor, tank, and lines.
  • Drain crankcase of four cycle engines and refill with clean oil.
  • Remove spark plug and pour one tablespoon of clean oil into the cylinder. Clean and replace spark plug or install new one.
  • Service air cleaner.
  • Tighten all loose screws and bolts.
  • Cover engine and store in dry place.

John C. Harper, II, Extention Agronomist.