Lawn Mowing and Related Considerations
Mowing is an important lawn management practice for both conventional and organic lawn and turf care. Consider the following in the management of your lawn or turf.
The leaf is the food factory for the grass. Mowing is stressful to grass and proper mowing is a key to a healthy root system and the health and quality of your lawn. The recommended mowing height of your lawn or turf grass is dependent on the grass variety. The publication, Turfgrass Maintenance in the Midwest recommends the following mowing heights for common lawn and turf grasses.
“Turf species Mowing height (inches)
Kentucky bluegrass 2 to 3
Perennial ryegrass 2 to 3
Fine-leaf fescues 2 to 3
Tall fescue 2 to 3
Creeping bentgrass ¼ to ¾
Zoysiagrass 1 to 1 ½
Buffalograss 2 to 2 ½
Bermudagrass ½ to 1”
Voigt, Tom; McPheeters, Ken. Turfgrass Maintenance in the Midwest. U5009. Urbana, IL. Vocational Agricultural Service, 1997
Routinely cutting grass shorter than these recommendations will increase grass stress; impact the grass’ ability to make food; deplete root food reserves and allow the lawn to be more susceptible to drought, insects, diseases, weeds and more. Scalping, the act of cutting the grass very short, on a regular basis will contribute to the lawn’s decline. Some turf uses for athletic purposes may require the turf to be mowed shorter than these recommended mowing heights. In these instances more intensive management will be required to maintain the vigor and health of the turf. Maintain the recommended grass height going into winter too. It may be beneficial to occasionally cut grass shorter during periods when grass seed is overseeded into the existing lawn to allow sunlight to reach the soil surface and for the soil temperature to increase.
To achieve the desired mowing heights adjust your mower deck height to your best estimate of the desired height. Mow a swath of lawn and then with a tape measure or ruler measure how high the grass is and adjust the mower deck as needed until the grass is cut at the desired height.
Mowing is stressful to grass and to help maintain the health and vigor of the grass it is recommended that no more than 1/3 of the grass height is removed at any one mowing. If achieving the recommended grass height would require removal of more than 1/3 of the grass then it should be achieved using several mowings with several days between each mowing to allow the grass more time to recover. For example using the mowing height recommendations above, if the lawn is predominately Kentucky bluegrass and is at a 6 inch height it should not be mowed to a recommended 3 inch height in a single mowing. Following the recommendation of removing no more than 1/3 of the leaf blade height would recommend that in the first mowing the grass be mowed to 4 inches. Several days later it should be mowed again and this time to the recommended mowing height to lessen the stress associated with mowing. Future mowing should be timed so that the recommended mowing height can be achieved in a single mowing. Mowing should occur as needed and not according to a calendar schedule. Within the range of mowing heights above I prefer to mow at the higher heights to support the grass’ ability to produce food and to benefit from weed control from a longer leaf blade shading the soil surface which helps prevent weed seed germination.
Mulch or compost grass clippings back into the lawn. If the lawn is properly managed the clippings do not cause thatch. The clippings will be decomposed by soil organisms and add nutrients and organic matter to the soil available for use by the grass. In a healthy soil environment the nutrients from the clippings can be available in the soil within a couple of weeks. Grass clippings may contribute up to 1/3 of the annual nitrogen and phosphorus requirements of common grasses and should be factored into the total nitrogen and phosphorus to be applied to the lawn. Returning the clippings to the lawn will save the homeowner the time associated with bagging grass clippings and the energy and other costs associated with disposing of clippings off site.
An exception to mulching grass clippings would be in instances where weed seeds such as dandelions would be broadcast throughout the lawn by mulching. In those instances it would be better to bag the clippings and remove them from the lawn and dispose of them appropriately.
Following mowing, sweep or blow clippings that landed on impervious layers back onto the lawn. Grass clippings that wash into drains and ditches may be a source of pollution.
Keep the mower blade sharp to prevent the shredding or further damaging of grass leaf blades. Shredding of the leaf tip can further stress the grass and may allow it to be more susceptible to diseases and pests.
Change mowing directions periodically to avoid grass damage from reoccurring mower wheel passes and so grass blades remains upright and don’t lean and develop grain in one direction. Keeping grass blades upright will facilitate mulched grass and leaves passage between the blades to make contact with the soil so soil organisms can break them down and incorporate it into the soil. Avoid tight mower turns that can damage the grass, especially for newly established grass.
When growing conditions are ideal there may be periods when grass cuttings clump on the lawn. This problem is minimized by not mowing more than 1/3 of the grass at any cutting and mowing when the grass is dry. Where clumping does occur be sure and disperse the clippings with a rake or blower.
Choose earth friendly practices. Choose organic lawn care.
Earth Friendly Land Care, Inc. (March, 2013)