This is easiest way to ensure the health of your lawn through the summer. When in doubt, just raise the mower all the way to its tallest setting. You never want to cut more than about one-third of your grass in any single session. Yes, this does mean you’ll need to mow with a little more regularity, but don’t fret: the growth of your lawn will slow considerably as the temperature average goes up. By maintaining a tall lawn, you deter weed growth and allow the grass to root deeper into the soil.