Usually, mowing the lawn once a week during the growing season should be sufficient to keep the grass healthy. The rest of the time, you can reduce the cutting frequency to every two weeks, as needed. During the peak of growth, mowing grass can leave unsightly rows or piles of wet clippings on the surface of the grass. Mowing the lawn more often will help avoid this problem.
You should trim the grass when the grass has grown 30 to 50 percent above the height at which it was previously mowed. If the grass is kept at a height of 2 inches, mow the grass again when it reaches 3 inches. If the grass has grown to 5 inches tall, you'll need to repeat the cut a couple of times, taking only a portion of the growth in each cut. Removing too much at once will only create more clippings that can shade the remaining grass and weaken it by removing too many active leaves.
Short cuttings will seep between the remaining leaves and decompose quickly. Having a mowing schedule encourages healthy and green lawns. You'll need to mow your lawn more often during your growing season, with an average of about once a week, depending on the type of grass. Usually, mowing the lawn weekly is the rule, but some lawns need to be mowed more often.
Other lawns will grow more slowly and may only need to be mowed once every ten days or two weeks. Usually, do not cut more than a third of the grass blade. More than that can damage the grass. Let the length of the lawn be what you judge, NOT the last time the lawn was mowed.