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Mowing

Mowing involves the periodic removal of turfgrass leaves and is the most basic and time intensive of all the routine turfgrass management practices. Mowing increases shoot density by increasing tillering (stems that develop from the crown of the parent plant) and ultimately improves site functionality.

Effective mowing height is determined by: grass species and variety, site use, level of management, desired field conditions, traffic level and other management practices. Turf mowed below or above the recommended cutting height for an extended period of time may not be able to perform as expected or desired.

Turf mowed too low and scalped routinely will have a reduced root system, shallow roots and lower stored food reserves resulting in a weakened turf which is more susceptible to pest pressure and requiring more frequent irrigation and fertilization. You can also expect the encroachment of aggressive weeds with lower turf density. 

Keys to proper mowing

Mowing height

Mowing at 3” or higher does not increase traffic tolerance. However, the turf will have a deeper root system and greater access to water and nutrients and will help reduce weed pressure.  The lower shoot density of higher cut turf can give a more open and shaggy appearance. During times when the fields are not in demand mow higher.

For increased density pick a mowing height and stick to it throughout the growing season. If you want to change the mowing height, reduce it gradually (in ¼" – ½" increments per week or mowings) to avoid removing excessive leaf area, scalping or weakening the turf.

There is no need to raise the cutting height in the summer on non-irrigated droughty sites. At this time almost all the root growth of cool season grasses is over until the fall so raising the cutting height won’t encourage deep root growth. However, more leaf area means more carbohydrates , the food source for plant growth.

If you get behind on the mowing and the turf grows much higher than desired gradually lower the height of cut over a couple of mowings. Think of returning clippings as providing free food, supplying nitrogen, phosphorus and some potassium. 

However, leaving excessive clippings on the field (besides looking unattractive) can smother grass, cause heat stress and keep the area beneath the clippings moist, providing an ideal environment for disease organisms to flourish.  The particular sport will ultimately determine mowing height. Based on grass species, the suggested mowing height is 2-2½" for Kentucky bluegrass and perennial ryegrass fields and  2½-3” for tall fescue. Keep in mind that mowing at the lower level will increase turf density.

Sport Recommended mowing height
Multi-use Fields, low budget fields 2.0 - 3.0”
Football, Soccer, Lacrosse,
Baseball Outfields
1.5 – 2.5”
High Quality Soccer Fields,
Field Hockey, Baseball Infields
1.0 – 2.5”

Mowing frequency

The frequency of mowing will depend on grass growth rate and the time of season.  Typically Kentucky bluegrass fields will require mowing at least twice a week in the spring and fall.  In the summer when the growth of cool season grasses slows down, if not irrigated, you may only need to mow once every 10 days.

Delay mowing fields when the soil is saturated to avoid soil rutting which will create unsafe field conditions that will impact footing and ball response. Also avoid mowing fields that are showing signs of drought stress.

Mowing efficiency

No matter what mowing equipment you use be sure to have the blades sharpened every 10-12 hours of use.  Sharpened blades provide a clean cut and more attractive appearance.  Dull blades leave ragged edges which contribute to disease occurrence and can increase fuel costs 20%.

Mowing is an essential but time consuming management practice. According to the 2003 NYS Turfgrass Survey, schools use 57% of their labor resources to mow their properties and parks use almost 70%. Determining the best mowing equipment is a critical management decision when looking at reducing labor costs.

Both reel mowers and rotary mowers are used on sports fields. Reel mowers are used on high quality fields where a lower cut is desired. Reel mowers are more fuel efficient and more expensive than rotary mowers and require extra maintenance.  They do best on relatively smooth surfaces. Rotary mowers are very common, affordable and versatile. A clean cut can be achieved with sharp blades and a high blade speed. They can cut taller grass but sharp blades are essential.  Care should be taken to control discharge when using rotary mowers where people may be nearby and to avoid excessive clipping piles.

How much time will it take to get the job done?

It really depends on the equipment you have. To mow an acre of turf it will take more than 2½ hours with a walk behind with an 18” width, about 30 minutes with a 60” riding mower and less than 10 minutes on a gang mower with a 20’ width.

Floyd D. Perry, well-known professional sports field groundskeeper, uses the following process to calculate how much time it will take to mow an acre:

  • Hours to mow an acre x 60 minutes = minutes to mow an acre
  • Use the factor 108.9 which includes the acres per hour dimension and a 10% time factor for turning at the end of swaths.
  • The mowing speed equals the miles per hour rating at the recommended mowing gear or the usual ground speed.

Example:

  • The normal, safe mowing speed of a ride-on mower is 3.5 mph. Assuming the mower deck width is 38 inches; multiply 3.5 times 34.2” (9/10 of 38”).  The product is 119.7.
  • Divide 108.9 by 119.7 and get the answer 0.909 or 0.9 hours.
  • Multiply 0.9 hours by 60 minutes to get the answer: 54 minutes to mow one acre.

Trouble shooting some common mowing problems:

Symptom Possible cause Correction
Brown, ragged blade tips
  • Dull mower injury
  • Sharpen blades
  • Replace blades as necessary
Brown, greasy spots or streaks
  • Leak in hydraulic system
  • Find leak and repair
Rippling or marcelling
  • Mowing too fast
  • Inform operator of proper mowing speed
    (check operating manual)
Brown grass, stems showing, no leaves
  • Scalping caused by mowing height too low, wrong mower used or excessive thatch
  • Readjust mowing height
  • Control thatch
Narrow strip of unmown grass
  • Damaged or nicked reel or bedknife
  • Grind or lap reel and bedknife until nick is removed.
  • Replace if necessary
Uneven mowing
  • Reels not set properly
  • Check reel units
  • Set mowing height evenly

Mowing pattern

Sports field managers use skill and creativity to design field striping patterns that are visually appealing to spectators. The patterns give a professional look to the field and do not affect playability.  By mowing in different directions the leaves reflect light resulting in the appearance of dark and light stripes.  The rear roller or the cutting heads on reel mowers provide the best stripes. New rotary mowers that have now added rear rollers on each cutting deck can also provide the striping effect.

Mowing direction should be changed every mowing. Grass will lean or grow in the same direction it is mowed so changing the mowing direction each time you mow will avoid the undesirable streaking appearance. Varying the mowing pattern also helps prevent scalping high spots and wear in the wheel tracks.