Friday, March 27, 2015

Watering In March

Yesterday, as temperatures surged into the lower 70s, I observed someone in my neighborhood watering their lawn.   So even with all the warm weather, should we be worried that our soil is already drying out?

But first, take a look at the amazingly warm temperatures on Thursday and keep in mind the average high on that date in Seattle is 55F!


Lots of 70s in western Washington and Oregon and 60s to the coast.

Although we have been MUCH warmer than normal, the precipitation has been close to normal for much of the winter.  Here is the % of normal for the last 30 days over Washington.  Wetter than normal over Puget Sound and MUCH wetter than normal over the NE Olympics and around Yakima.  A bit drier than normal in some other locations...but not by much.  No drought in Washington State.

So water is reaching the ground.  Warmer temperatures and more sun could mean more evaporation, but that is probably a small effect this time of the year.  But what does the U.S. drought center say?  

For example, they have a Crop Moisture Index (see below)...and that suggests that soils west of the Cascade crest are relatively moist (dark green).
The Palmer Drought Inde, which is more of a measure of long-term drought, is also wet over western Washington, but California is quite dry.
And it looks like we will receive enough moisture to keep the ground wet for a while.  Here is the forecast precipitation total for the next 72 hrs.  The Olympics and north Cascades will get plenty of water and southern BC will get hit fairly hard.


 My own personal experience is that here in Seattle one doesn't have to start watering until late May in dry years and late June in wet years.

So if you want dry, head to Yakima, eastern Oregon, or south.   And don't water your grass now....it doesn't need it.


2 comments:

Karin Corbin said...

maybe he was watering in the moss killer ;)

wdolson said...

There is actually a good reason to not water your lawn when the rains stop. The soil in the west is great for growing crops because of our dry summers. As soil dries, ground water in the several feet below the surface is wicked up closer to the surface and the plants use that water.

The process carries nutrients nearer to the surface so less fertilizer is needed.

When the rains stop, I usually wait until the plants and grass start looking a little stressed before I turn on the sprinklers. I never fertilize the lawn and while it doesn't look like a golf course, it looks at least as good as my neighbors who dump lots of fertilizer on their lawns.

(I live in the Portland area, but much the same climate as Seattle, just a bit drier and a bit warmer in the summer overall.)