Many factors influence the right way to water or irrigate your lawn grass. And while no two yards or landscaping situations are exactly alike, the basics are pretty much universal for most lawns.
Lawn grass and plants in general like infrequent deep watering rather than frequent shallow watering. As a rule, if you water shallow you'll have shallow roots and if you water deep you'll have deeper roots.
Whenever you water your yard, apply enough to moisten as much of the root zone as possible. Use a probe or shovel to determine what the average rooting depth is in your yard and then water as long as needed so the soil is moistened to that depth.
It's important to know how deep your roots go and your soil type so you can calculate how many inches of water you'll need. For clay soils, apply 1.5 inches of water to saturate six inches deep. For sandy soils, as little as .5 inches may be needed.
To figure how long you'll need to water to get a certain amount of saturation, simply place several small saucers, or cans, or other objects in the watered area. Watch the clock. Whenever most of your saucers reach close to your desired level, make a note of the time. Water for that amount of time.
How Often and How Long
Grass lawns like a deep watering and then time to dry out somewhat between waterings. As a rule and depending on your soil type, weather, and grass type, your total water from rain and irrigation per week during the growing season should be .75 - 1.5 inches.
How often you have to water to get this amount of saturation depends on a few things. On sandy soils you should split your water cycle into more than one cycle. If you apply the entire amount, the water will flow right by the roots and little will be used.
On clay soils you should also split the cycle as watering all at once will cause too much runoff and evaporation. Watering a hillside or slope is the same and requires special attention.
Time Of Day
The most efficient time of day to water is late evening and early morning. It generally is less windy, cooler, and more humid at this time. You'll have less evaporation and more efficient use of water. Water pressure is generally better because fewer people are using water at this time so you'll get better coverage. Generally, watering at night doesn't cause any disease growth.
For more specific information on individual grass types, see Lawn And Yard Grass Types. There you will be able to get information on individual lawn grass species as well as water and irrigation requirements.