Question
I would like  to know how many times per week and how long to water St. Augustine. I have pop-up sprinkler heads with good coverage. I live in southern California.  

Answer
Water once, maximum twice, weekly. When you do water, try to water deeply. The general goal is to water 1" per application. To find out how long time to run your sprinklers to apply 1", try to place straight sided cans in the sprinklers path (such as tuna cans, drinking glasses, empty soup cans, etc but not bottled with tapered sides; only straight sided). Turn the sprinkler on and run it for 30 minutes. Turn it off (or you will get wet). Go back and meassure the height inside the cans with a ruler. If the water height inside the cans have reach 1", it takes your sprinklers 30 minutes to apply 1" of water. If the height on average inside the cans is only 1/2" it takes your sprinklers 60 minutes to apply 1" of water.

When watering, try to water infrequently and deeply. Preferably set the sprinklers to come on in very early morning hours when wind is less, the sun can dry the lawn during the day reducing chance for disease, and when water pressure in the neighborhoods typically are low.

Watering frequently and shallowly is not recommended on established lawns.