Time to Irrigate
With the exception of newly planted plants, I have not had to irrigate until this week of hot weather. Even now there is still moisture in the soil available for deep rooted plants. When hot weather finally comes, sometimes we panic and turn the sprinklers on every day. Again, with the exception of newly transplanted plants, daily watering is not necessary and is even detrimental in some situations. Brief daily watering keeps the top of the soil moist, which encourages weed seed germination. It also encourages moss growth on top of the soil in shady areas.
The best way to irrigate is to apply enough water to wet the entire root system of shallow rooted plants like grass. Then allow enough time for the soil to dry on top. Depending upon your sprinkler system, it usually requires a minimum of 20 minutes to apply enough water to wet the soil several inches deep. Rotating sprinkler heads may require an hour or longer.
If your soil will not accept that much water at one time without runoff, run sprinklers through the cycle twice at half the amount of time.
You can determine how long it takes to deliver 1/3 to 1/2 inch of water using your sprinklers by placing shallow cans such as tuna fish cans on the lawn. Water for a specific interval such as 30 minutes and then measure the accumulated water with a ruler.
Run sprinklers through their cycle on a two minute cycle so you can check them at least once a month. This will allow you to catch plugged or mis-aligned sprinkler heads before dry spots develop.