The amount of water your plants need and when it is needed changes with the weather, length of day, and root depth. Regularly adjust the watering schedule of your automatic irrigation system (unless you have a smart timer) to maintain healthy, beautiful plants and avoid wasting water.
In the Pacific Northwest the watering season usually lasts from April to September. Check this page weekly for advice on programing your sprinkler timer for the upcoming week.
This week’s watering advice
- Updated: Friday, April 25, 2025
- Conditions: The soil is still wet under the surface.
- Watering Recommendation: Don’t water established plants!
Some sprinkler timers come with a water efficiency feature called seasonal adjustment that uses historical weather data to simplify changes to watering frequency. This feature, which is represented by a percentage, allows you to instantly adjust the runtime for all sprinkler system zones. For example, if the runtime is currently 10 minutes but April has a 53% seasonal adjustment, the new runtime will be 5 minutes.
To use this feature, set the runtimes and frequency of watering as if it is the hottest time of the year. Then, change the percentage of the seasonal adjustment each month. Here are the percentages for each month based on historical weather data:
- April = 53%
- May = 74%
- June = 83%
- July = 100%
- August = 81%
- September = 48%
Do you want to save even more water than simply using historical seasonal adjustment percentages? Are you ready to replace your old sprinkler timer with a new weather-based sprinkler timer? Weather-based timers can reduce your landscape water use by up to 25%. You may be eligible for up to a $100 rebate! Learn more about the program and eligibility requirements.
Do you need professional assistance? Check out this short list of local certified landscape professionals!
Choosing the right run time for your system
Each watering should apply a ½ inch of water. The application rate of a sprinkler system depends on the water pressure, system design, and system efficiency. Below are some general ranges of typical run times based on the precipitation rate of your sprinkler heads:
| Head Type | Nozzle Description | Run Time* for a ½ inch | If Using Cycles** | |
|---|---|---|---|---|
 | Spray Head | Sprays like a fan | 15-23 minutes | 3 cycles of 5-8 minutes |
 | Rotor Head | Single spray that rotates | 30-75 minutes | 3 cycles of 10-25 minutes |
 | MSMT Head | Multiple single sprays that rotate | 50-75 minutes | 3 cycles of 17-25 minutes |
**Cycling Recommendation: To prevent runoff and ponding in areas with clay soils and/or slopes, divide the run times into three cycles to allow the ground to absorb the water. Additional cycles are created by utilizing more than one start time combined with shorter runtimes.
Weekly watering advice straight to your inbox
Sign up for the Weekly Watering Advice Email. We’ll send you a short email once a week with our watering advice and tip between April and October each year.