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.

If the turf is mowed too low the crown, where leaves are initiated, can be damaged. Photosynthetic capacity necessary for root and rhizome development will be reduced if too much top growth is removed.  So turf that is routinely scalped will have a reduced root system, shallow roots and lower stored food reserves. The result will be a weakened turf which is more susceptible to pest pressure and will require more frequent irrigation and fertilization. With lower turf density you can expect the encroachment of aggressive weeds. Increased mowing heights will influence ball roll, however, a study conducted by Kevin Trotta, well- known grounds manager at North Rockland Central Schools, showed that increasing the mowing height did not influence athlete speed performance. The previous facts and findings should be shared with coaches, players and others who demand low cut turf.

Craig: Insert Cultural intenstiy spectrum image here?

Importance of 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.  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 and 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 but more leaf area means more carbohydrates (the food source for plant growth).

Follow the 1/3 rule, which means never remove more than 1/3 of the leaf blade per mowing.  If your desired height of cut is 2" you will need to mow when the grass reaches 3".  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 and phosphorus and some potassium.  Keep in mind that 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 heights for Kentucky bluegrass and perennial ryegrass fields is 2-2½ " and for Tall Fescue 2½-3".

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”

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.

A recent Michigan study showed that when the mowing frequency was increased from once to twice a week the number of soccer games played in a season was increased from 17 to 25. Increasing the mowing frequency (resulting in improved turf density) may be one way to help meet increasing field-use demands.

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 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.

Craig: Insert Diagram 2, Figure 1 (excessive clippings), Figure 1 (batwing mower).

Craig: 1//3 rule needs updating

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:

  • Note: 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.

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%.

A few 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 stripping 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 stripping 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.