You might have heard that you should water your lawn for an hour at a time, or that it needs a heavy dousing one or two times a week.
But Dr. Guy Fipps, irrigation engineer at the Texas AgriLife Extension, says that’s not very precise.
“Then the tendency is you go out there and you run your sprinklers for longer periods of time, without really a strategy in what you’re doing. And you may end up wasting water and spending a lot more money on your water bills than you need.”
So how do you determine the right amount of water for your lawn? If you wanted to figure it out on your own, you’d
need to use a complicated mathematical equation called the Penman Monteith equation. But no need, Fipps has done the work for you.
“We have a couple of weather stations in the Houston area and we have a website and you go and you click on the station that’s closest to where you live. And there’s these calculators that will come up and they’re pretty much self-explanatory.”
So on the website you just pop in some info about the type of grass you have and whether your yard gets full or partial sun.
The one bit of real work required is to measure how much water your sprinkler puts out per hour. You can use a rain gauge or even an empty tuna can set in the yard to collect the water and then measure it with a ruler. Fipps says he waters his own yard twice a week, using a total of only four-tenths of an inch of water, just enough to keep it alive.
For lawn calculations, use the irrigation calculator.