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  MG Manual Reference
Ch. 12, pp. 29 - 35

[Maintenance: irrigation | new lawn | fertilization | renovating | mowing | mowing heights
| dethatching | aeration | weed ]


Mowing Height Recommendations
  Mowing Height during..........
Species Normal Weather High temperature stress periods

Bermudagrass 1-1 1/2" 1 1/2-2"
Chewing fescue 1 1/2-2" 2-3"
Creeping red fescue 1 1/2-2" 2-3"
Hard fescue 1 1/2-2" 2-3"
Kentucky bluegrass 1 3/4-2 1/4" 2 1/4-3 1/4"
Perennial ryegrass 1 1/2-2" 2-3"
St. Augustinegrass 1 1/2-3" 2-3 1/2"
Tall fescue 2 1/4-3" 2 1/2-3 1/2"
Zoysiagrass 1-2" 1 1/2-2 1/2"

Suggested Mowing Heights for Desert Turfgrasses (inch)
Low Maintenance
  Base Mow At Base Mow At Base Mow At
Tiffgreen bermuda (419) 1/4 3/8 --- --- 3/8 5/8
Tifway bermuda (318) 1/2 3/4 3/4 1 1/4 1 1 3/8
Santa Ana bermuda 3/4 1 1 1/2 1 3/4 2 2 1/2
Midiron bermuda (EZ turf) 1 1 3/8 1 1/2 2 2 2 1/2
Common and other seeded lawn type bermudas 1 1 3/8 1 1/2 2 2 2 1/2
Zoysia Japonica 1 1 3/8 1 1/2 2 2 2 1/2
Buffalograss 1 1/2 2 2 1/2 3 3 4
Perennial ryegrass 1/2 3/4 1 1/4 1 3/4 2 2 1/2
Annual ryegrass 1 1/2 1 7/8 1 3/4 2 1/4 3 4
St. Augustine 1 1 3/8 1 3/4 2 1/4 2 1/2 3
Tall Fescue 1 3/4 2 1/4 2 1/2 3 1/4 3 1/2 4 1/2

Mowing a turf at the low end of the allowable height range has the benefits of: (1) increased shoot density, and (2) narrower leaf width (finer texture). Disadvantages, include less food for root, rhizome and stolon growth, since mowing itself is a stress. During periods of summer stress, increase the height of cut when possible. This will allow for more root growth, as well as insulation of the base of the plant where the shoots come from. If you follow these tips, something else is the cause of poor turf.
Mowing More Effectively

Mowing is a stressful process. Because grasses look good when they are mowed, you may assume they thrive on mowing. Grasses do not thrive on mowing; they merely tolerate it better than do other plant species. Lower mowing heights increase stress because they reduce leaf area, which decreases the plant's ability to photosynthesize. As photosynthesis decreases, the plant's stored food supply is lowered, rooting is restricted and the ability to survive stress periods is reduced.
What should you do? During periods of extended high temperature and drought, raise the mowing height and don't remove more than one-third of the above ground portion of the grass at any one time. This is particularly important in stress periods.
Be sure your mower has a sharp blade. University tests have shown that mowing bluegrass with dull mower blades reduces lawn quality because of leaf spot disease, reduced shoot density and less leaf growth. Tests also show that mowers with dull blades use 22 percent more gasoline than those with sharper blades.
Mowing Patterns

Mowing Patterns to Discharge Grass
Mowing tips

  • Mow your grass regularly. This encourages it to spread horizontally, to thicken and to choke out weeds.
  • Cutting grass short is not the answer to a good-looking lawn. Cutting grass to a uniform height is what gives your lawn a neat appearance.
  • Remove no more than one-third of the grass blade in any one mowing. When you cut off more than one-third, you remove the green material that absorbs sunlight and manufactures food that is stored in the root system. The grass plant goes into shock and parts of the deeper root system die back.
  • Mow at the highest setting recommended for your type of lawn. The taller the grass blades are above the ground the deeper the root system is below ground. A large, deep network of roots helps grass plants withstand stress during drought and hot weather.
  • Keep the mower blades sharp. Dull blades shred the tops of the grass blades and can make entry wounds for diseases. Shredded grass tips turn brown quickly and look unsightly. Mow in a different direction every time. Otherwise, grass plants tend to develop a grainy appearance, especially at low mowing heights. Overlap swaths by 2 to 4 inches to achieve a uniform cut.
  • Avoid mowing your lawn when the grass is wet. A dull blade can actually pull grass plants out of wet soil. Tires on heavier equipment are more likely to compact the soil on wet ground, thus impeding the movement of air and water into the soil
  • During rainy weather, it is better to mow wet grass than to let it get too tall.
  • If you must mow overly long grass, take steps to avoid overloading the mower engine. Cut only a half to three-quarter swath rather than full width. A better technique is to mow the lawn twice, cutting only one-half the required amount on the first pass lower the mower and mow at the desired height on the second pass.
  • If you mow often enough, the short grass clippings will filter down into the grass and do not need to be removed. Clippings return about 25 percent of the required fertilizer to the soil when they decompose, and are a source of organic matter. Remove long clippings which remain on top of the grass, preventing them from excluding sunlight or encouraging disease development when wet.
  • Thatch is a layer of dead stems and roots that can act like a sheet of plastic to impede the necessary movement of water, nutrients and pesticides into the soil. A 1/2 in. thatch layer is beneficial. If you have more than one-half inch, use a dethatching machine with vertical blades that slice through soil and kick out thatch debris.

Mowing Equipment

Walk behind power mowers manufactured after June 30, 1982, for sale to consumers in the United States must meet certain safety requirements by the Consumer Product Safety Commission. Walk behind rotary mowers must have a blade control system and must meet specified foot probe testing and shielding requirements. The blade control system must:
  • Prevent the blade from operating unless the operator activates the control.
  • Stop the blade rotation unless the operator continues to hold the control down.
  • Stop blade motion within 3 seconds after the control is released.

Walk behind rotary mowers also must have at least a 120 degree rear foot shield.
Three types of blade control systems are permitted: the extended rope (ERS) or zone start, the electric alternator start (EAS) and the blade brake clutch (BBC). When the deadman control lever is released on ERS and EAS mowers, both the blade and the engine continues to run. All three systems must have the restart mechanism located within 24 inches from the top of the mower's handle. Walk behind rotary mowers with a cutting width of 30 inches or more, a weight of 200 pounds or more and an engine of 8 or more horsepower are exempt from the standard.
BBC mowers should be returned to idle speed before releasing the control/stop lever. Failure to do so will cause excessive wear and shorten the life of the blade-brake clutch stopping mechanism.
The amount of time you want to spend mowing is important when choosing a lawn mower. A flat, 1 acre lawn with no obstruction can be mowed in about an hour with a riding mower. It will take 2 to 3 1/2 hours with a 21- inch walk behind mower and you'll walk 6 miles. A lawn tractor can mow an acre in 45 minutes to an hour.
Maintenance tips

Check the oil level in the engine crankcase while the engine is on a level surface and the engine is turned off. If the oil level is below the full mark, add the engine oil recommended in the operator's manual. Don't over-fill the crankcase because this causes hard starting, plug fouling, and engine damage. Remove grass clippings, twigs and other debris from the engine shroud, air intake screen, grille and side panels because this material could block air movement and cause the engine to overheat. Debris may also interfere with the movement of the mower drive belt, if so equipped.
Check V-belts in the engine area. A slight unraveling does not indicate premature belt failure. You can cut off the unraveling when the cover begins to peel. If there is extreme or abnormal belt wear, check for faulty sheaves and replace. Otherwise, wipe V-belts with a clean cloth and replace oily, greasy belts. Don't use belt dressings because they soften the belt and shorten its life.
Reel mowers must be sharp and aligned properly with the bed knife, which is the straight sharp bar on the bottom of the mower. A properly sharp and adjusted reel should cut a one inch wide strip of newspaper cleanly and still allow the reel to spin with minimal resistance, A tight reel will squeal and overheat.
Sharpen Those Blades!
Sharpening the mower blade
After 40-60 hours of use, reel mowers should be back-lapped and adjusted. After 250 hours, it should be reground. Most lawn repair shops will backlap and reset a reel mower for around $30.00. Grinding is slightly more expensive.
How to sharpen blades

Remove the blade according to the recommended procedure described in the operator's manual. Be sure the engine cannot start accidentally while you're working on the mower, disconnect the spark plug wire. Protect your hands from the cutting edge of the blade. Sharpen the blade with a file or grinding-wheel attachment on an electric drill. Make sure the blade is balanced or have this done professionally.
Balancing the mower blade
Storage tips

Warm up the engine and drain crankcase oil. For most lawn mowers that are used in warm weather, refill the crankcase with 30-weight oil.
Empty the fuel system every autumn. Drain the system and run the engine until all remaining fuel is used up to help prevent a buildup of gum from old gasoline. Or add a gasoline stabilizer, a chemical that helps prevent the settling out of varnish and sludge. Dealers report that leaving old gasoline in the engine over winter is the number one cause of hard starting or failure to start in the spring.
"Pickle" the engine. Remove the spark plug and pour 1 tablespoon of SAE 30 engine oil into the cylinder. Crank the engine twice to distribute the oil on the cylinder walls and replace the spark plug. This helps prevent corrosion.
Check all visible parts for wear, breakage and damage. Make any necessary repairs to avoid delays next season, and spray-paint scratches to prevent rust.
Block a tractor or riding mower to take weight off the tires. Store mower in a cool, dry, dark place away from sources of flame that could ignite any fuel vapors.
Tips for safe operation

  • Clear the lawn of debris and stones before each mowing.
  • Keep children and pets a safe distance away from mowers.
  • Never take passengers
  • Keep feet and hands away from blade when starting and running the engine. Wear heavy shoes, preferably with non-slip soles.
  • Always push the mower rather than pulling it toward you.
  • Mow across slopes with a walk-behind mower and up and down slopes with a riding mower.
  • Never reach into the mowing chamber while the blades are under power, as to dislodge clippings from the discharge chute.
  • Refuel the engine only when it is shut off and cool. Always use a funnel.
  • Protect the grass from fuel spills by never refueling on the lawn.
  • Handle fuel safely.
  • Stop the engine and disconnect the spark plug wire before working on the engine or blade.
  • Keep all safety devices in working order.
  • Reading and following the operator's manual, which the manufacturer carefully prepared, is your best assurance of safe, long-term equipment use.

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