The one inch myth

I've heard it a bazillion times. The "appropriate" amount to water your lawn is one inch of water weekly. Landscapers, sales people, even my local nursery says this is the case.

Then I do the math: 52 inches of water a year for a lawn? In natural conditions, it only rains 36 inches a year in Seattle. Even if I back out the water naturally produced by rain, this is a lot of water to feed the lawn. Does a lawn really need subtropical conditions in order to thrive?

Clearly it doesn't. Over watering makes plants lazy and gives them weak root systems. The grass comes to depend on the excess water and can even become unhealthy.

So what's the *right* amount to water? What's the right time? Day or night?

Paul suggests in his great lawn care article:

Two methods to tell when it is time to water:

    * The grass will start to curl before it turns brown. When it starts to curl, that is the best time to water. Anything after that is time for "intensive care watering" (water half an inch, wait three hours and water an inch).

    * Take a shovel and stick it into the soil about six inches. Keep the sun to your left or to your right when you do this. Push the handle forward. If you can see any moisture, wait. If it's all dry, water. If you can't get your shovel to go into the soil this deep, you need more soil.

Is it really ideal to wait until the grass is almost brown though? Is this too risky? What if we forget and then lose the grass? There has to be some kind of happy medium...

I need to update my article. 

An inch of water on the surface should water the soil about twelve inches deep.  But if your soil is only two inches deep, this amount of water is a really bad idea.

On another path:  you mention 52 inches of water because there are 52 weeks in the year.  But for cold season grasses, there are many months that you don't water becase there is plenty of rain, and there is the cold months where you don't water because it isn't going to grow anyway.

Plus, if your soil is really deep and your grass is trained to go deep for water, you might need to water only one time over the whole summer!

glad to have seen this.......I am holding out for my lawn to begin to curl, as a side note. I often get lucky by doing so, and it rains.Less work, eh? I will water after the rain if it is a light one,curl or no curl,  i figure. Plus with our coastal climate we get alot of dew-wop.

I am a little weary on my 4-5 month ago installed sod in the back, but the ground is still moist not very far down. my soil is deep.