With all the misconceptions and confusion surrounding cutting heights, many homeowners and haymakers are likely cutting their grass too short. When cut at a lower than ideal height, grasses activate stress responses that cause later issues and damage to the stand.
In a recent Ohio BEEF Cattle Letter article, Christine Gelley, an extension specialist at The Ohio State University, explains the repercussions of cutting grasses too low and how to find the right height for your grass.
“Depending on grass species, variety, and environmental conditions, mowing height and frequency can vary greatly,” Gelley explains. She advises to be aware of where new growth occurs on the grass stem and how deep the root system goes.
The region on the stem where the new growth emerges is called the apical meristem. When that region is mowed off, the plant has to produce a new shoot called a tiller in order for regrowth to occur. This process draws extra nutrients from the root system.
When grasses are cut too short on a regular basis, root energy reserves are depleted, which result in nutrient deficiencies and low-stand persistence. These problems make stands look patchy, and weeds begin to fill in the holes.
Most producers will fertilize, irrigate, and apply herbicides to remedy the damage from cutting too short. “In most cases, the problem is not soil fertility, water in the soil, or that new weeds are suddenly invading,” Gelley explains. “More likely, it is the reduced ability of the plant to draw the nutrients and water from the soil.”
According to Gelley, the general rule when mowing lawns is to remove one third of the total leaf area. For hay production of cool-season pastures, mow or graze before seedheads develop, and down to 3 to 5 inches. For warm season pastures, mow or graze down to 8 to 10 inches for proper regrowth.
Gelley concludes, “Mowing at a higher height in the canopy will improve the health of your grass stand, reduce the presence of weeds, and improve the quality of your soil, giving you a thicker stand of desirable grasses.”