By Clint Waltz
Georgia Extension Service
In your yard, you may consider mowing a necessary evil. But when you do it right, mowing can be the single greatest contributor to a good- looking lawn.
Mowing affects a turf's density, texture, color and uniformity. But few people understand its real benefits. Even if you water and fertilize your lawn correctly, its overall quality is compromised if you don't mow it properly.
Mow for your grass type
Different turf grasses require different mowing heights. Hybrid Bermuda grasses, for instance, should be mowed every three to four days to keep them at 0.5 to 1.5 inches high. Keeping the slower-growing centipede turf at 1 to 2 inches requires mowing only every five to 10 days.
Other turfs' best mowing heights and frequencies include:
- Zoysia, 0.75 to 2 inches, three to seven days.
- Common Bermuda, 1 to 2 inches, five to seven days.
- Tall Fescue, 2 to 3 inches, five to seven days.
- St. Augustine, 2 to 3 inches, five to seven days.
Mowing heights and frequencies can change, of course, depending on fertilization and soil moisture. But mowing at the wrong height can harm the turf's rooting, which in turn affects how the shoots grow and take up water.
Mowing carefully decreases disease and other problems, too
Weeds and diseases are more likely, too, if you cut the grass too high or, more commonly, too low. Cut at the proper height, a turf grass's canopy can reduce the light penetrating to the soil, making it harder for weed seeds to germinate.
Improper mowing can make a lawn less tolerant of stresses like temperature extremes and traffic, too. No question about it: for a healthy lawn, use the correct mowing height.
Time mowing properly
Mow the lawn with a sharp blade when the grass is dry. This spreads the clippings better and keeps down diseases. Mowing wet turf causes clumps of clipped grass to remain on the lawn, which limits sunlight from reaching the leaf blades. The resulting yellow spots can be pretty ugly.
Mowing when the soil is too wet can also compact the soil more and can slow the grass's rooting.
Mulching v. bagging
You may wonder whether you should bag your lawn clippings. If you mow it properly, leaving the clippings is a good idea. In fact, there are several advantages to leaving the clippings.
For one thing, clippings build up the soil organic matter, which makes it easier for water to move into the soil and helps the soil retain water and nutrients.
There's no evidence that returning clippings to the turf can help build up harmful thatch. Soil microbes efficiently break down the clippings into organic matter. And the decomposition process can reduce nitrogen needs by 25 percent.
Don't let clippings blow into storm water systems or surface waters, though. This can clog systems and pollute water sources. If the clippings need to be bagged, try composting and using them as a soil conditioner or mulch.
Follow the 'one-third' rule
Decide when to mow based on the "one-third rule." Never remove more than one-third of the leaf tissue at any one mowing. Removing more than that or cutting the turf too low can lead to a weak turf stand, decreased rooting and a host of other preventable problems.
A good guide is to mow the turf when it is 50 percent taller than the desired height. For example, if your turf should be maintained at 2 inches high, mow it when it reaches 3 inches.
Letting the grass overgrow the "one-third rule" hurts the turf. But mowing too often is harmful, too. Mowing too often can allow diseases to enter the leaf tips more easily. Other negatives include increased wear, soil compaction, labor expense and wear-and-tear on mowing equipment.
(Clint Waltz is a Cooperative Extension turf specialist with the University of Georgia College of Agricultural and Environmental Sciences.)