Horticulture News: Mowing height means a lot to the health of your lawn

By Amanda Sears/Madison County Horticulture Agent, Published:

It’s hard to believe that it is already time to mow again. And, in spite of the cold snap during the week, many of you may have already mowed.

The shorter you cut your grass, the more often the lawn will need mowing. Also, mowing higher will reduce weed infestations and improve rooting depth of grasses. Keep in mind, most of our lawns are tall fescue, which should be kept between 2 to 3½ inches.

Kentucky bluegrass lawns should be kept within the same height range as tall fescue lawns. The other major cool-season grass, perennial ryegrass, should be kept shorter, between 1½ to 2½ inches. Warm season grasses, such as Bermuda grass and zoysiagrass, have a much lower optimum height, 1 to 2 inches and 1 to 3 inches respectively. 

Never cut off more than 1/3 to 1/2 of the blade at a time. Removing more than half of the leaf blade causes scalping which can kill some plants and will increase the likelihood of weeds. That also reduces root growth and weakens the plant.

Cool season grasses, which make up the majority of our lawns, grow the most in April and May, so these months will be the peak of the mowing season.

Mowing tips

Do not mow during the midday when the temperature is near or over 90 degrees Fahrenheit and the soil is dry.

Don’t bag up and throw out grass clippings. Leaving them on the ground returns nutrients back to the soil. They should not add to or cause a problem with thatch.

Make sure that they are spread uniformly across the lawn so as to not shade grass blades. If you do not want the clippings to remain in your yard, take them to a compost pile.

Keep your mower blades sharp. They should be sharpened several times a year. A dull mower will shred leaf tips and give a brown tint. Dull blades also have been shown to increase fuel consumption, cause excessive wear on the engine, belts and bearings and increase the buildup of clippings which stay under the mower deck.

Mow when the foliage is dry. Mowing when the foliage is wet increases the chance of disease transmission and clumping of clippings.

For more information on mowing, check out the University of Kentucky publication, Mowing Your Kentucky Lawn at www2.ca.uky.edu/agc/pubs/AGR/AGR209/AGR209.pdf.

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