A good lawn can be ruined in one season by cutting the grass too short. Assuming you have a good one, it takes proper fertilizing, watering and mowing to keep it that way. Mowing is the most important.

The green blades of grass manufacture food for the plant and when too much is removed it seriously interferes with root development. As soon as the grass thins a bit, weeds start to invade. High mowing favors thick turf development, that is, heights up to 2 to 2 1/3 inches for bluegrass, perennial rye and fescue. Bermuda and soysia can be mowed much closer because they form stolons.

Research has shown that removal of 70 percent of the green matter stops all root growth. Stoppage of root grwoth failed to take place only when less than 40 percent of the foliage was removed. In other words, if the grass is 3 inches tall, no more than 1 inch should be removed at one time.

Grass with a good root system has the ability to crowd out weeds and prevent them from becoming established. The grass is green and healthy. It can better withstand the heat and drought of summer and is less likely to be seriously damaged by turf diseases and insects.

Recommended mowing heights for Kentucky bluegrasses are 1 1/2 to 2 inches, red fescue 2 inches, tall fescue such as Kentucky 31, 2 1/2 to 3 inches. Bermuda and zoysia, 1/2 to 1 inch. Many of the newer varieties of bluegrass such as Fylking, Pennstar and Baron can be mowed closer, at about 1 1/2 inches.

The rule of thumb in mowing is to remove no more than one-third of the green leaf area at a time. If you miss one or two mowings and the grass gets guite tall, raise the mowing height for one or two mowings and gradually drop it back down to the original height. Do not try to remove all of the growth at one time or you may seriously damage the grass.

Usually it is necessary to mow every three or four days incapable of generalizations," he says. "This is not ery week or 10 days during the summer when growth is slow.

Adjust your mower, when it is resting on a flat surface such as the sidewalk, so that its cutting edge is at least 2 inches above the flat surface, or at whatever other height you may cut the grass.

A dull blade on a rotary mower will tear or shred the grass instead of cutting it cleanly. The lawn looks sort of overcast afterwards due to frayed brown ends of grass blades. If you use a rotary, examine the cutting tips of the blade every time you mow the grass. It is a good idea to have two blades for the rotary, one to be used while the other is being sharpened. The blade may need it several times during the season.

There are two opposing opinions about removal of grass clippings. One says that every single clipping should be picked up for a more attractive lawn. The other says they should all remain on the lawn for mulch and protection. Actually both are partly right. A lawn does look better without a layer of clippings, and there is considerable value in letting the clippings decompose on the lawn. too many clippings, however, may choke off air and this would be bad for the grass.

It is a good idea to vary your pattern of cutting. Go back and forth in one direction for one cutting, then the opposite back and forth the next time. Even cut diagonally sometimes. Continual cutting in the same way tends to slant the grass in that drection.