Watering your grass isn't an exact science, but you mustn't overwater or underwater it. Underwatering causes dormant grass while overwatering can flood the yard, having a negative effect by reducing soil oxygen supply. Water your grass every other day, either early in the morning or after dinner. Because the mornings are usually colder, the water can be absorbed before it dries in the sunlight. Watering in the early evening ensures that your grass receives some sunshine while also allowing it to dry before it becomes fully dark. In terms of amount, rain or manual watering should provide your grass with roughly an inch of water each week. Stick a knife or other instrument into the soil to test the moisture level, and if it is wet 6-8 inches deep, your grass is appropriately watered.