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, September 19th
- Conditions: The weather has been mild with periods of rain, and it will continue this way into next week.
- Watering Recommendation: Don’t water unless the soil has dried out a few inches beneath the surface. If the soil has dried out, water shallow-rooted plants like lawns a ½ inch every 10 days and water deep-rooted plants like perennials, shrubs, and trees slowly to a depth of 6 inches. A deep layer of arborist woodchips on top of the soil will help reduce evaporation and increase the number days before needing to water again.
Lawns Need Less Water in the Fall
Most lawns in western Washington are categorized as cool season grasses, meaning they prefer cooler temperatures, which is why most lawns go dormant quickly in the hot summer months without supplemental water. The current favorable conditions of cooler temperatures and occasional rain may make it unnecessary to give your lawn additional water. When temperatures get colder your lawn will move into its winter dormancy. Learn more about lawn care here.
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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