Between the excessive heat and lack of rain last summer, trying to keep a lawn green has been a losing proposition. Given the great need to conserve water to make it last through the ongoing drought, not being wasteful by overwatering your yard is extremely important.

But how does one judge if just the right amount of water is being applied to keep the grass healthy? Now there is an online tool that can help you work it out.

The Texas AgriLife Extension Service at Texas A&M University has developed on online calculator that will allow people to apply within a 10th of an inch the amount of water their turf grass needs. That’s no small feat given the amount of misinformation out there about watering amounts, says Dr. Guy Fipps, AgriLife Extension irrigation engineer.

“Look at garden sections in newspapers and elsewhere, you’ll typically see recommendations like water 1 inch to 2 inches a week, or that you should water infrequently and deeply — vague concepts like that,” Fipps said in AgriLife Today, the extension service’s online magazine.


But the online calculator allows people to plug in specific information about their area. It uses weather data from 30 automated scientific weather stations around the state. It also takes into account the type of grass, amount of sunlight it gets and other factors, before spitting out a number of inches of water needed to sustain a lawn.

Once the calculator provides the recommended watering amount, the next step is to determine your sprinkler’s watering rate. There is a simple, low-tech way to do this. Put out one or more empty tuna cans in the yard and turn on the sprinkler for 30 minutes. Then, get a ruler and measure the water’s depth in each can. Double that amount and you get how many inches of water your sprinkler puts on the lawn in an hour.

You can then take that number and plug it in to the online calculator and it will tell you how often and for how long you should water each week. To begin using the calculator, go to www.texaset.tamu.edu. For more conservation ideas, go to www.brazos.org/conservation.asp.