The dry, hot weather continues, and some lawns may be taking a beating. One recent Boston Globe article re-emphasizes an important tip for keeping lawns healthy, growing and protected from drought harm. You should cut your lawn on a higher mower setting. According to the story, “Your grass should be 3 inches high. Grass needs to stay that tall to absorb moisture and shade its own roots. By cutting it shorter when it’s already turning brown, you’re drying out the soil around the roots and stressing the grass more.”
And it points out the bottom line – you have two options: Tolerate the brown period as a natural dormancy stage that grass plants go through to protect themselves from drying out at the roots. Or keep watering, but do it the right way — deeply, 1 inch a week — while obeying local watering rules.
Read more here http://www.boston.com/yourtown/news/milton/2010/07/lawn_care_tips_for_a_hot_dry_s_1.html