THE RIGHT HEIGHT

            Proper mowing height depends primarily on the type of grass.  The rule of thumb is to mow so that no more than one-fourth to one-third of the grass blades are removed during mowing.  For example if you normally mow your lawn at 2 inches, mow when it is about 2 1/2 inches tall.

            The penalty for not paying attention to the recommended mowing height is a stiff one.  By letting grass grow too high and then cutting away half or more at one time, you expose stems that have been shaded and may burn in strong sunlight.  If the lawn is yellowish after you mow, you have waited too long.  The grass will recover and grow back, but more important, roots are severely shocked by heavy mowing and may need several weeks to recover.  Research has shown a direct relationship between the height of the cut and the depth of roots. When grass is properly mowed to its recommended height, roots grow deeper.  In turn, a deep root system makes lawn care much easier because the lawn is in overall better condition and health.

            Grasses tend to spread either horizontally or vertically.  For instance, bentgrass and bermudagrass spread horizontally by creeping rhizomes and stolons.  Because these stems parallel the ground as well as the cut of the mower, they are not normally mowed off.  Unless these grasses are mowed low, preferably with a heavy reel mower, they will have problems with thatch.

            For the most part, warm-season grasses can tolerate closer mowing than cool-season grasses.  If cool-season varieties are mowed too low (at 1 inch or less), they usually begin to produce roots less vigorously, lose their deep green color, and show signs of thinning.

            At low cutting heights, diseases such as dollar spot, leaf spot, and rust are more of a problem because they can envelop the whole plant more quickly.  Grass that is allowed to grow to its recommended height not only resists diseases better, but also helps shade and cool the surface of the soil, preventing many weeds from germinating.

            Warm-season and cool-season grasses growing primarily in the shade should be allowed to grow approximately ½ inch higher than their normal recommended cutting range.  This provides more leaf surface for the food-producing process of photosynthesis.

            In general, lawns going into winter should be cut at the midpoint of their cutting range or somewhat shorter, rather than left long during the winter.  This prevents the grass from matting and the excess leaf blade tissue from decaying.  If given this final mowing, the lawn will have better color during the winter (in mild climates) and will green up sooner in the spring.