The frequency of weekly watering depends on your grass species, total water requirements for the week, and how long your soil will absorb water before running off into the gutter.

Warm-season grasses

Warm-season grasses have extensive root systems that penetrate deep into the soil and require deep and infrequent watering. Water as few times a week as necessary to fulfill your weekly water requirements without causing excessive runoff. Usually 1 or 2 times a week is sufficient.

If you want to determine the maximum amount of time your sprinklers can be left on at one time, observe a cycle from the beginning to the time when runoff begins. That is the maximum amount of time that you let your sprinklers run in any given watering. Space out the applications evenly during the week.

Cool-season grasses

Cool-season grasses require more frequent watering than warm-season grasses because their root systems are not as extensive. Divide the required weekly minutes into about 3 equal irrigations, evenly spaced throughout the week. Fewer applications may be sufficient during cooler months. Desert areas, slopes or areas with shallow soils also need shorter, more frequent irrigations than warm-season grasses.

1. In Sacramento during the month of May, a tall fescue lawn is growing and requires 42 minutes of water per week. How should the irrigation be scheduled?

Water once a week for 42 minutes.

Water twice a week for 21 minutes each day.

Water 3 times a week for 14 minutes each day.

2. In the Los Angeles area, a St. Augustinegrass lawn requires 48 minutes of water per week during the month of June. However, runoff occurs when the sprinklers have been running for 18 minutes. How should you schedule your irrigation?

Run the sprinklers 2 days a week for 18 minutes each and run them 12 minutes on a third day.

Run the sprinklers for 16 minutes a day, 3 times a week.

Run the sprinklers 4 times a week for 12 minutes each.