   Warm Season Lawn Mowing - July 21, 1999 Jeff Schalau, County Director, Agent, Agriculture & Natural Resources Arizona Cooperative Extension, Yavapai County Midsummer is the peak of the warm season turf growing calendar. Warm season grasses lie dormant all winter. Once the mercury begins to rise in mid-April, warm season turf grasses begin to green up. They grow vigorously through the summer then slow down and ease into dormancy in mid-October. Varieties of warm season grasses that well suited to the Verde Valley are bermudagrass, zoysiagrass, and buffalograss. St. Augustine is also a warm season grass, but is not recommended for our area. Many lawn owners are misinformed about how to care for turf. The most common misconception is: mow your lawn as short as possible to avoid frequent mowing. Low mowing actually stimulates turf growth and triggers a stress response in the grass. This stress is a negative effect on the grass and increases water consumption, increases fertilizer (nitrogen) demand, and reduces lawn density allowing weeds to establish. Correct mowing height is determined by the species and variety of grass being grown. Common bermudagrass should be mowed 1 to 1 1/2 inches in height during normal weather and 1 1/2 to 2 inches during high temperature periods. Hybrid bermudagrass should be mowed 1/2 to 1 inch in height during normal weather and 1 to 1 3/8 inches during high temperature periods. Zoysiagrass should be mowed 1 to 2 inches in height during normal weather and 1 1/2 to 2 1/2 inches during high temperature periods. Buffalograss should be mowed 2 to 3 inches in height during normal weather and 3 to 4 inches during high temperature periods. The number one rule of lawn mowing for all species and varieties is: never remove more than one third of the height of the grass at one mowing. If more needs to be removed, do it gradually over the next couple of mowings. The longer the blade length, the more leaf area the plant has. Greater leaf area allows it to produce more photosynthate (sugar) and store more energy in the roots. This stored energy is a reserve that allows the grass to survive stressful periods. Grasses don't thrive on mowing, they merely tolerate it. The number two rule of lawn mowing is: keep the lawn mower blade sharp. Dull lawn mower blades whip the grass rather than slicing it cleanly and caused what Dr. David Kopec, University of Arizona Turf Specialist, calls the dreaded silver leaf tip disease. Most homeowners have rotary lawn mowers. These have a single blade that rotates at high rpm on a plane parallel to the lawn surface. The other style of mower is the reel type. Reel mowers are designed for close mowing (less than 1 1/4 inches). These have several blades arranged in a circular, twisted pattern that snips the grass against a fixed blade called the bed knife. Lawn mowers are dangerous and care should be taken when using them. Follow the instructions that came with the mower and do not remove any of the safety equipment. Before sharpening the blade(s) always disconnect the spark plug wire or unplug the mower. Sharpening the blade on a rotary mower is not difficult, but the blade needs to be balanced as well. Reel mower sharpening is more difficult and requires more specialized equipment. Contrary to popular belief, leaving the grass clippings on the soil surface contributes very little to thatch build-up when proper mowing is practiced. With proper mowing height and frequency, clippings will decompose rapidly. However, excess clippings left on the lawn will weaken the turf. If long blades are sitting on top of the grass, then they should be removed. Mulching mowers chop the clippings in finer pieces and increase the decomposition rate. At any rate, allowing clippings to stay on the lawn will decrease fertilizer needs by up to 25%. Some final lawn mowing tips. Avoid mowing wet grass, but during rainy weather it is better to mow the grass wet than let it get too tall. If it does get too tall, cut only one third of the total height at any one cutting. You may even need to only cut a one-half to three quarter swath rather than full width. When leaving the clippings on the lawn with a side discharge mower, mow in the direction that puts clippings onto the area that has already been mowed rather than concentrating the clippings in the center of the lawn. Cool season grasses are somewhat dormant during the summer. Most of this information (aside from mowing heights) can also be applied to cool season turf types. The University of Arizona Cooperative Extension has publications and information on turf culture and fertilization. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 or E-mail us at mgardener@kachina.net and be sure to include your address and phone number. |