Mowing too short can harm your lawn

There’s probably no more common cultural practice than mowing the lawn. University of Missouri Extension specialists warn against overdoing it.

“Folks think that if they mow short they can mow less often, but that’s not the case,” said Brad Fresenburg, an MU Extension state turfgrass specialist. “By mowing short you’re actually creating stress on the plant and that creates a shorter root system.”

In Missouri the majority of lawns consist of a mixture of cool-season grasses like tall fescue and Kentucky bluegrass. Set your mower deck to a height of 3-4 inches to optimize the health of those grasses.

“Taller grass gives a shade effect that prevents annual weed seed germination, and just taking mowing height from 2.5 to 3.5 inches reduces annual weed populations by up to 80 percent,” Fresenburg said. “When we move into the drier months of July and August, the grass comes under more heat and drought stress, so there’s a tremendous benefit to mowing taller that creates a healthier plant with a deeper root system as well as good competition against annual weeds.”

To determine mowing height, don’t trust preset adjustments on your mower. Instead, Fresenburg recommends using a tape measure from the ground to the bottom of the cutting blade.

Blade sharpness can also have a significant impact on the heath of a lawn. Sharp blades create more of a scissor-type cut, which reduces the opportunity for turfgrass diseases to establish.

“If you notice that clippings or the leaf tips themselves start to look shredded or jagged, that’s a good indication that blades need to be changed out or sharpened,” he said.

Some people also make the mistake of keeping too neat of a lawn. By always raking or bagging clippings homeowners can significantly deplete important nutrients.

“We always like to say, ‘Mow tall and let the clippings fall,’” Fresenburg said. “There’s tremendous benefit to not raking, and if you return clippings to a lawn you can return up to 30 percent of your seasonal nitrogen as well as 50 percent of your seasonal potassium.”

While the time for overseeding has passed, homeowners still have a few options for fertilizing. Organic fertilizer or slow-release nitrogen are recommended at this time of the year.

“There’s little chance of burn or overfertilization because organic fertilizer is slow-release,” Fresenburg said. “Get out there and measure your lawn first. Know the square footage and then you can determine how much fertilizer you need.”

Find more lawn care tips at http://ppp.missouri.edu/newsletters/meg/archives/v12n4/meg5.htm and http://ppp.missouri.edu/newsletters/meg/archives/v13n3/meg1.htm.