The answer to this question varies as greatly as the climate across the country. The amount needed on the Gulf Coast of Texas would starve grass planted in New Mexico. Region, grass type and soil all play a part.
I’ll attempt to give some general answers first. Then I’ll try and get more specific.
An often used rule of thumb is that your lawn should receive at least 1 to 1 ½” inch of water per week. However, how often you water also depends on weather, area restrictions, grass types and more. Under watering is as common as overwatering. It may be more common, especially during high heat times. Under watering causes shallow roots, making the grass more vulnerable to stress. Eventually the grass turns brown and dies.
Many are not aware of the problems caused by over watering. Your lawn needs moisture, nutrients, and air to grow. If you water too much, you can saturate your soil to the point where air cannot get to the roots. The lawn basically suffocates. So a water balance is very important.
Generally you want to water in such a way that the water penetrates 6” to 8” into the soil. This helps establish deeper roots for your grass. On a recent test in a public park in Houston, Tx, a generally well watered area, grass roots were found going down more than 12”. This is an example of the difference between a little every day and a lot on one or two days a week in absorbent soil. Look at the root depth chart that follows.
Another consideration is how short you cut your grass. Taller grass helps shield the soil from heat and retains moisture better. Try to avoid extremely short settings on your mower.
After all this I still haven’t told you how often to water your yard. Ok. Here’s my answer, sort of. Figure that your grass needs about 1” to 1.5” per week. You also want to water in such a way that it soaks into the soil to enough depth to encourage root growth but does not run off due to non-porous soil or sloped yards. Look at this illustration:
In clay you might want to water three or four times a week, about ¼ inch per time, twice a day. Since clay absorbs water so slowly you won’t risk water runoff. With sand you can have water absorb past the depth the grass can use it. In this case you might water ½” at a time, three times a week. This should keep it moist. In loam you can often get away with twice a week, ½” to ¾” at a time. The loam will absorb and hold the water for a long time. Remember to water in the early morning, before the wind and sun comes up to dry out the yard.
There really is no set rule – every other day, once a week, or every third day. The best thing to do is be in tune with your lawn. By doing so, you will notice signs when your lawn needs a drink.
I would like to offer one piece of advice that I know is good: get to know your local nursery or your area county agent. Also, most areas have a college that does research into local growing patterns. Their information is very valuable and usually free. The lawn in Maine varies greatly from that in Louisiana and that in Oregon. You local experts are your best resource.
For More Information
For more information about anything involving irrigation, please visit us at www.SprinklerWarehouse.com.