Most turfgrasses can survive seasonal dry periods without irrigation and therefore can be used in any water-use zone. In moderate-water-use zones, turfgrass is irrigated only when it shows signs of moisture stress.

Turf under water stress appears dull bluish green, the leaf blades roll inward, and footprints remain on the grass after a person walks over an area. To prevent serious plant damage and maximize water-use efficiency, irrigate turf in the moderate-water-use zones with a portable lawn sprinkler within 24 to 48 hours after these signs appear.

Under optimum growing conditions in a high-water-use zone, turfgrasses use 1 to l l/2 inches of water per week during hot, dry weather. It is usually best to divide this amount into two applications per week, applying l/2 to 3/4 inch each time. Never apply more than 1 inch at a time as this will likely result in runoff or deep percolation below the root zone. Early or late in the season when temperatures are cooler, irrigating only once a week is usually adequate.

Never water grass daily except during the establishment period. Daily irrigation with a small amount of water encourages a shallow root system and reduced drought tolerance, as shown in Figure 4. Since roots generally grow where the soil is moist, a shallow root system also prevents efficient uptake of plant nutrients. Shallow, frequent irrigation also increases evaporative water loss from the soil.