How Often Should I Run My Sprinklers in Fall? The optimal time to run a sprinkler in Fall is 30-35 minutes a day for 2-3 days a week. Keep your lawn and plants healthy year-round with our ultimate guide. A common misconception is that homeowners don't need to water their lawns during the fall as the period is not truly considered the "growing season." However, this isn't precisely true. Your lawn still requires some moisture during the colder months, so it's best to be proact