To keep your lawn healthy and weed free it is important not to cut it too short. The grass should not be mowed shorter done about 3 inches long. Otherwise it goes brown during the heat of the summer. It is also more susceptible to the growth of weeds.
Grass should be mowed regularly. By doing this the length of the grass cuttings is kept short and they can decay and actually contribute to providing nutrients for the growth of further along . Otherwise the clippings accumulate on your lawn leading to the accumulation of thatch which hinders the growth of the grass.