Weekly Lawn Watering Schedules

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If you want to keep your lawn green all summer long, the amount of water your lawn needs changes every week according to the weather and length of day. Regularly adjusting the watering schedule of your automatic irrigation system (unless you have a smart timer) will help you maintain a healthy, beautiful lawn and avoid wasting water.

In the Pacific Northwest the lawn watering season usually lasts from June to September. Check this page every week for our advice on how to program your sprinkler timer for the upcoming week. 

This week’s lawn watering advice

  • Updated: Thursday, September 21st
  • Conditions: We have had an unusually dry summer and the Seattle Regional Water System is facing a potential water shortage this fall. We are asking customers to voluntarily reduce their water use- including stopping watering lawns for the rest of the season.
  • Number of watering days: 0 days

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 DescriptionRun Time* for a ½ inchIf Using Cycles**
Shows a sprinkler head spraying water in a wide, flat, fan-shaped stream. Spray Head Sprays like a fan 15-23 minutes3 cycles of 5-8 minutes
Rotor Head Single spray that rotates 30-75 minutes3 cycles of 10-25 minutes
MSMT Head Multiple single sprays that rotate 50-75 minutes3 cycles of 17-25 minutes
*Runtimes calculations: Each sprinkler nozzle type has a specific precipitation rate measured in inches per hour. Spray nozzles operate between 1.3 and 2 inches per hour. Rotor nozzles operate between 0.4 and 1.0 inches per hour. MSMT nozzles, or multi-stream multi-trajectory nozzles, operate between 0.4 and 0.6 inches per hour. From these ranges the runtimes were calculated to water a ½ inch.

**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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