When watering your lawn, you should really strive to water enough to wet the entire root zone. The most common error committed by people is light irrigation. Too little water too often encourages a multitude of problems such as shallow root system. The ever changing need for watering depends mainly on your soil and of course, the weather. Determining the type of soil you have is really helpful when determining beneficial watering schedules. If you have a clay based soil watering to 1.25″ +/- is just about right. However if your soil is more sandy or loam than anywhere between 1/2″ – 3/4″ is fine. Try to remember that rainfall is no guarantee and should not be relied on as the single source of moisture for your lawn. Light showers merely wet the surface. Short down pours do the same. Most of the water is lost in runoff before it can soak in to the soil. A lawn will use as much as two inches per week in hot, dry weather – a fraction of that when it is cooler. If you decide your lawn needs water, you should put on enough to wet the entire root zone as specified above. If you can, avoid late afternoon or evening irrigation. Grass that stays wet for a long time favors development of diseases. However, do not avoid watering at these times if this is the only time you can water. The important thing is water. Avoiding late afternoons is secondary to providing the needed water to your turfgrass. In heavy clay soils prevent watering to the full recommended amount at one time, frequent watering may be necessary to avoid surface runoff.