AGR-54
A.J. Powell Jr.
Good lawn care takes more than just mowing and chemical treatments. To develop quality turf, you need correct mowing techniques and may occasionally need to dethatch, core, or roll your lawn.
Some of the most serious mistakes in lawn care include mowing lawns too closely, mowing too infrequently, or using a dull mower blade.
Height of Mowing
Check your blade height and follow these guides for your grass:
| Grass |
Mowing Height |
| Kentucky Bluegrass |
|
| Tall Fescue |
|
| Creeping Red Fescue |
|
| Perennial Ryegrass |
|
| Bermudagrass |
|
| Zoysiagrass |
|
Below-optimum mowing heights greatly restrict root development, and the grasses become susceptible to disease, heat and drought damage, traffic injury, and weed infestation. If mower height can be adjusted, slightly increase the height for bluegrass and tall fescue lawns during the summer and lower the mower height slightly below optimum during late fall. Never allow these grasses to go into winter at tall height. As long as the grass grows in the fall, keep mowing.
Adjust your schedule according to how fast the grass is growing. Mow often enough so that no more than one-third to one-half of the turf height is removed at any one mowing. For example, if you are mowing at 2½ inches, mow again when the turf reaches a height of approximately 3½ inches. If your grass gets excessively tall, raise the mowing height so you do not cut off too much at one time. Instead, mow every two or three days, gradually lowering the mower back to the original height.
A sharp mower blade makes mowing easier and results in a better-looking and healthier turf. Reeltype mowers are preferred, but a sharp rotary mower gives a clean cut and is easier to maintain than a reel-type mower. Rotary mower blades need sharpening two or three times per year.
Nicked and dull mower blades cause severe tearing of the leaf.
Lawns can be severely damaged if you mow during midday when the temperature is near 90°F or higher and the soil is very dry. If you must mow under these conditions, wait until the temperature is cooler in the late afternoon or early morning, until you can irrigate, or until rainfall occurs. It also helps to raise the mower height and mow less frequently during severe heat/drought periods.
Clippings are not harmful if your mower spreads them uniformly and if they are not so thick they shade the grass below. Clippings can aid the grass by returning nutrients back to the soil, and they do not cause thatch problems. However, removing clippings when heavy disease is affecting the grass may help prevent further spread of the disease.
The rotary mower may be the most dangerous tool you own. Safety rules follow:
Thatch
Thatch is a tightly intermingled organic layer of dead and living shoots, stems, and roots that develop between the green vegetation and soil surface. A neglected lawn will never accumulate thatch; a wellmanaged lawn may. Thatch most frequently develops when:
A little thatch is desirable, since it helps moderate temperature extremes at the soil surface and provides a cushion effect on the surface. But an accumulation of ½ to 1 inch of a dense thatch creates problems because it interferes with water and air movement into the soil and creates a favorable environment for insects and diseases.
To combat thatch, use a dethatching implement or vertical mower that cuts through the thatch to the soil surface. As it passes through the grass, dead and living organic material is cut, torn loose, and deposited on the surface. If ½ inch or more of thatch is present, it may be necessary to cross the lawn two or three times in different directions. Operation of dethatching machines is relatively easy, since they are partially self-propelled. Most difficulty occurs on steep slopes or when soil is very dry.
A good thatching machine has fixed knives or sling blades; spring tines are not effective.
Select a dethatching machine that cuts with knives or blades. Some machines have flexible, leaf rake-type tines that are ineffective in removing thatch. Spring tines that can be attached to your rotary mower blade are not good for dethatching either, and can cause severe mower damage. Dethatching equipment can often be rented from lawn equipment rental companies.
The organic material dislodged by the dethatching machine should be removed and composted or discarded. It can be raked into piles or onto plastic sheets or a tarpaulin and placed in garbage bags or dumped in a truck. Several garbage bags or a full pickup load of thatch can be removed from just a small lawn.
A thatch layer of ¾ inch or thicker is usually most easily removed with a sod cutter. When cut just above the soil surface, the highly organic strips of sod are very light and easy to handle. Of course, the lawn must be reestablished after the thatch and live grass are removed.
Bluegrass lawns should be dethatched only in the fall or spring, never in summer. For bermudagrass, remove thatch in early to midsummer. Tall fescue and perennial ryegrass turf never develop enough thatch to be a problem. Zoysiagrass may develop a serious thatch problem, but dethatching it is not recommended, since zoysiagrass requires several months to recover.
Aerification is a term used interchangeably with the terms core cultivation or coring. This method of turf cultivation involves using equipment with hollow tines or spoons to remove soil cores from the top 2 to 3 inches of soil and redepositing the soil cores on the surface. Good aerifiers are sometimes available from rental agencies, and most lawn care companies offer aerification.
The cores will disappear after significant rainfall or irrigation.
In contrast to aerification, cultivation practices that do not remove soil (i.e., spiking and slicing) do not improve the surface. They give little or no benefit and may increase surface compaction.
Coring helps:
Thatch reduction occurs because the extracted soil mixes with the dead organic matter to create a natural compost. During wet weather, however, the cores from heavy clays will be very sticky on shoes, clothing, and mowing equipment.
To make aerification worthwhile:
Rolling is not often considered a regular maintenance practice. In fact, rolling wet, heavy clay soils will cause soil compaction and decrease soil aeration. However, on well-drained, medium, and coarse-textured soils, rolling may help:
Germination and seedling development are very poor in loose, droughty seedbeds.
With good moisture, a heavy roller will help remove minor roughness in the soil surface.
Water-ballast rollers can often be rented. These rollers have a hollow drum that can be filled with water. By increasing or decreasing the amount of water in the roller, you can adjust the weight to give a firm seedbed or smooth a surface. If the lawn is sloping, a small garden tractor may be necessary to pull the roller. Rolling is most beneficial when the soil is moist, not wet.
