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: Thursday, July 26th
- Conditions: In the 70’s with clouds and some sunny afternoons
- Watering Recommendation for non-weather-based sprinkler timers: Water established, shallow-rooted plants (like lawns) ½ inch every 5 days. Water your established, deep-rooted plants, like trees, shrubs, and perennials, slowly to a depth of 6 inches.
When and How to Water More Slowly
If your soil is anything but sandy, then water your plants slowly. Water infiltrates into clay or silty soil until the spaces between particles plug up and causes the water to pool or runoff. To get water to move deeper into clay or silty soil, use sprinklers that apply water more slowly or use 3 start times and cut your runtimes into thirds. When water infiltrates deeper into your soil, you can water less frequently, and the roots will grow deeper.
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.
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