It soon will be time to dust off the lawnmower and get ready to begin spring lawn care. Properly cutting grass directly affects the health and quality of a lawn. Another ingredient of an attractive lawn is to allow ample time to properly adjust the mower and to maintain it throughout the grass-cutting season."Two serious lawn-care mistakes are mowing too closely and too infrequently," said A.J. Powell Jr., Extension turf specialist with the University of Kentucky College of Agriculture."Mowing below the optimum species height restricts root development and makes grass more susceptible to heat and drought damage, traffic injury and weed infestation," he said. "Removing several inches of top growth will scalp grass and may smother grass below when the clippings create a 'wind-row.' Check the mower blade height and mow grass at the best height for that particular species."Powell recommended a mowing height of two to two and one-half inches for Kentucky bluegrass, tall fescue and creeping red fescue; one to two inches for perennial ryegrass; one-half to one inch for Bermuda grass, and three-fourths to one inch for Zoysia grass.The mowing frequency depends upon how fast grass grows, according to Powell."A rule of thumb is to remove no more than one third to one-half of the grass height at any one time," he said. "For example, if you mow grass at a height of two and one-half inches, mow again when it is about three and one-half inches tall. If grass becomes excessively tall, raise the mowing height to keep from cutting off too much grass at one time; then mow every two to three days, gradually lowering the mower to the desired height. Never let grass go into the winter at a tall height; keep mowing as long as the grass grows during the fall."There are several reasons mowing frequency is important. Cutting off more than one-third of the grass at one time can stop root growth. It also will require more frequent watering to keep the plants alive during dry summers. Following the one-third-removal rule will produce smaller clippings that quickly disappear into the grass canopy to remain hidden from the surface.To improve safety, older mowers should be replaced by newer models with modern safety equipment. Review the manufacturer's directions and operator's manual for safe operation before lawn-care season begins. Perform regular maintenance, or have someone do it, being sure to check for worn or loose tires, belts, guards and covers. A sharp blade makes it easier to mow and results in a more attractive, healthier lawn; whereas, a nicked, dull blade severely tears grass leaves. Although reel-type mowers are preferred, a sharp rotary mower gives a clean cut and is easier to maintain than the reel-type mower. Rotary mower blades should be sharpened two or three times during the mowing season.Should you remove grass clippings? It depends, according to Powell."Clippings are not harmful if your mower uniformly spreads them and they are not so thick that they shade the grass," he said. "In fact, clippings may help grass by returning nutrients to the soil. Clippings do not cause thatch problems. If you have a severe grass disease problem, removing clippings may prevent further disease spread."The local Cooperative Extension office has more information on mowing and other lawn-care practices.