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The Homeowners Column
Guidelines for Mowing Lawns
Extension Educator, Horticulture
For better or worse the drone of busy lawn mowers is heard throughout the summer. I do, however, prefer the clack, clack, clack of people-powered reel mowers. Sometimes a few grazing sheep seem like a gentler, quieter option but then you have to worry about more than just piles of grass clippings on the lawn.
Despite what we may believe, lawn mowing is more than one more landscape chore. Actually how a lawn is mowed can have an impact on lawn appearance and lawn health. Here are a few simple guidelines for proper mowing.
Mow at the proper height. Something as simple as raising the mowing height can have a major impact on the quality of many home lawns. Lawns mowed at higher heights tend to have deeper roots, less weed problems, and look better. Scalping opens up areas of the lawn to weed invasion. Unless golf balls are involved, don't mow it short. Mowing the lawn short may seem like a good idea so you don't have to mow as often. Letting the lawn get tall, than mowing it short is not a good idea. For most lawns, a mowing height between 2 to 3 inches is best. When the weather is cool and the grass is growing rapidly, the two-inch height is fine. As the weather gets hotter and drier and grass growth slows, height should be raised to three inches. In shade mower height should also be mowed at the three-inch level. The first and last mowing of the year should be at a height of about 2 inches; avoid scalping in spring and allowing the grass to remain excessively high at the end of fall.
Avoid removing more than one-third of the leaf blade at any one mowing. In other words don't let the grass get above three inches to mow it to two inches. I know this is tough when the grass is growing fast. If the grass gets out of control, don't immediately mow it to two inches but instead gradually take it down to the lower height over a couple mowings. Try to mow at the rate of grass growth rather than the day of the week. Also don't mow when the grass is wet.
Return clippings to the lawn when feasible. Unless you see big piles of grass left after mowing, clippings do not need to be collected. Small clippings readily decompose (contain 75 - 80 percent water) and do not cause thatch. Clippings also recycle nutrients, in particular nitrogen, so less fertilizer is needed. Mulching mowers are not really necessary. A study at the University of Illinois showed mulching mowers did not provide any additional benefit over conventional rotary mowers returning clippings, assuming proper mowing frequency and lawn fertilizing was followed.
Keep mower blades sharp. If the grass blades look ragged and straw-colored on the tips, it's time to sharpen blades. Torn grass blades lead to leaf disease problems and detract from the lawn's appearance.
Mow in the direction that is safest. Mowing in criss-cross patterns or periodically mowing in different directions is fine, but not really necessary unless golf balls or boredom are involved.
Do not over-fertilize. Over fertilization can lead to excessive growth and water pollution. The amount of fertilizer needed depends on grass species and lawn owner expectations. Do not apply more than one pound of actual nitrogen per 1,000 square feet per application. About 3 pounds (no more than 4) of nitrogen per 1,000 square feet per growing season is suggested for most full-sun lawns, about half that for shady lawns.
Consider reducing areas to mow. Replace lawn areas with groundcovers. Research electric or non-motorized mowers to reduce air pollution. Check out our website for more great info on lawns. http://www.urbanext.uiuc.edu/lawntalk/