Lawns across Iowa have turned a beautiful, dark green in the last few weeks. The greening of lawns signifies the arrival of spring and the start of the lawn mowing season. Proper mowing practices over the next several months will help keep the lawn attractive and healthy.
Mowing height and frequency are the most important aspects of mowing. Kentucky bluegrass lawns should be mowed at a height of 2 ½ to 3 inches in the spring and fall months. Set the mower blade to a height of 3 to 3 ½ inches during summer. A higher mowing height in summer helps to cool the crowns of the turfgrass plants and provides more leaf area for photosynthesis during the stressful summer months.
Mowing frequency is based on the growth rate of the turfgrass. As a general rule, never remove more than 1/3 of the total leaf surface at any one mowing. For example, to maintain a lawn at 3 inches, the grass should be mowed when it reaches a height of 4 ½ inches. In spring it may be necessary to mow every 4 to 5 days, once every 1 to 2 weeks may be sufficient in summer, with more frequent mowing again in the fall. Irrigation and fertilization practices and weather conditions dictate mowing frequency.
Mowing grass that is too tall is hard on the mower and, more importantly, is harmful to the grass. Removing more than one-third of the leaf area weakens the turfgrass, reducing its ability to withstand environmental stresses. Another problem is the large amount of clippings. Excessive amounts of clippings are unsightly, tend to smother the turfgrass, and create an environment that favors disease development. Grass clippings may need to be bagged or raked and removed when mowing grass that has grown too tall.
Grass that has grown excessively tall should be mowed as soon as possible. Raise the mower blade as high as possible, mow, and (if necessary) remove the grass clippings. Gradually reduce the height of the grass in later mowings until the lawn is being mowed at the proper height.
When the lawn is mowed properly, grass clippings do not need to be removed or bagged. Small clippings filter down into the turf and quickly decompose, returning essential plant nutrients to the soil. Lawn clippings do not significantly contribute to thatch development.
Mow the lawn with a sharp blade. Sharpen the mower blade each spring. Thereafter, periodically inspect the blade and sharpen as needed. A dull blade tears the ends of the grass blades. The damaged tissue dries out giving the turf surface a whitish appearance. Also, the torn leaf tissue loses greater amounts of water and increases the possibility of disease problems.
Alternate your mowing pattern or direction each time the lawn is mowed. Repeatedly mowing the lawn in the same direction pushes the grass over rather than cutting it cleanly. Also, different mowing patterns reduce soil compaction and wear from the mower wheels.
Whenever possible, mow the lawn when the grass is dry. Wet grass is more difficult to cut and occasionally clogs rotary mowers. Also, it's safer to mow the lawn when the grass is dry as there is less risk of slipping and being injured by the mower.