In general, you want the top 6 – 8 inches of soil to be moist, but not soggy – which translates to 1 – 1.5 inches per week. The precise number of minutes for each watering will vary from lawn to lawn, depending on factors like the size of your lawn, the type of sprinkler you have, and its settings. Watering deeply, but infrequently, leads to stronger root development and drought-resistance than watering briefly every day. You can break up these waterings into twice a week during most of the year, or three times a week during the hot summer months.