In hot weather, raising the lawn mower blade an extra quarter of an inch will do wonders for keeping your grass green. Most lawn mower blades only go up to three inches, so raise it to the highest setting. Some specialty mower blades can go as high as six inches. The longer you leave your grass, the longer the roots will grow. Deeper roots allow for better moisture retention, and a hardier lawn. Longer grass helps shade the soil, which prevents it from drying out, and also prevents weeds from germinating.