Lawns in western Washington don’t require irrigation to survive. If you don’t mind a brown lawn during the summer, your lawn will green up again when the rains return in the fall. Watering deeply once a month in summer helps to keep the roots alive. In the fall you can thicken any worn areas by raking and then overseeding.

Trying to keep a green lawn through the summer?

If you do want a green lawn during the virtually rain-free summer months, plan on giving your lawn about 1 inch of water per week to stay green.

Do a “tuna can test” to find out how long your sprinklers take to supply 1 inch of water to your lawn:

1. Place several short, straight-sided, empty containers (like tuna or cat food cans) on your lawn.Be sure to place some near the edges of the sprinkler spray area and some near the center.
2. Turn on the sprinklers for 15 minutes.
3. Measure the depth of water in each container with a ruler. Determine average depth.
   

   Distribute containers throughout sprinkler’s spray area.

4. Use the average depth to calculate how long to run your sprinklers so that you give your lawn 1 inch of water per week. (The table below can help you calculate.)
   

 

 

 

 

 

If your sprinkler has a high output or puddles occur while you are watering, it is best to spread this time over 2 to 3 waterings so that water soaks down to the roots, rather than running down the sidewalk and into storm drains. Watering deeply and less often moistens the whole root zone and is generally best for plant health.