The most frequent mistake is mowing lawns shorter than they should be cut. For most lawns, keeping the mowing height between three and 3.5 inches is ideal - mow a little taller during the heat of summer. Lawns mowed at higher heights tend to have deeper roots, less weed problems, and have a much healthier and greener look. Mowing too close invites problems such as weed invasions. Simply raising the mowing height can have a major impact on the quality of many home lawns. Mowing at a lower height when grass is growing quickly is fine, but the height should be raised as growth slows or stress increases, Shady lawns should be mowed a little higher as well..
Yards should be cut according to the growth rate of the grass. Do trim more than one-third of the leaves of the grass in any one cutting. Mowing as the lawn needs it is essential. In the spring, this will likely mean more than once a week. It is never advisable to mow when the grass is wet.
Another issue related to mowing is whether clippings should be collected. As long as the lawn is mowed on an as needed basis and the one-third rule is followed, clippings will readily filter back down into the lawn, and need not to be collected. The clippings readily decompose (they contain 75 - 80 percent water) and do not cause thatch. Clippings also recycle nutrients, in particular nitrogen, so less fertilizer is needed.
The newer mulching mowers create even finer clippings, recycling the nutrients more often as the smaller clippings decay faster. Mulching mowers do not perform at peak efficiency if the lawn is too tall (removing more than one-third of the grass blade) or if the lawn is wet.
Another critical area overlooked by homeowners is maintaining a sharp mower blade. A sharp mower blade will cut the grass blade cleanly. This gives the lawn an even appearance and reduces disease from damage caused by a dull mower blade. Mow in the direction that is safest. Periodically change directions if desired, although mowing the same direction each time should not be a problem on taller turf typical of home lawns. The first and last mowing of the year can be slightly shorter, not so short that you scalp the lawn. Scalping in spring and allowing the grass to remain excessively high at the end of fall encourages weed and disease problems