Watering…
Each watering should moisten the soil to a depth of 3-5 in. This is the active root zone. The length of time and amount of water it will take to moisten the root zone depends on soil type and the irrigation system. Ideal times to water are 4AM to 6AM.
Water will penetrate sandy soils more quickly and more deeply than clay soils. Running your water sprinkler for 15-20 minutes, three times a week should provide enough water to keep your lawn healthy and looking good. A thick healthy lawn will help against the germination of weeds.