By Clint Waltz, Ph.D. – University of Georgia Turfgrass Specialist
Turfgrass Spring Blog #4: 2020 Edition
All living things need water to survive, albeit a different amount for different organisms. For plants, supplemental water from irrigation is sometimes needed between natural rainfall events. Fortunately, turfgrass is a fairly robust plant that needs relatively little water for survival.
Many factors influence the amount and frequency of water needed for turfgrass within a home lawn. Soil type, type of grass, fertility level, frequency of rain, temperature, wind, and humidity all affect the amount of water needed. A high-level fertilization and hot, windy days tend to increase the demand for water, while low level fertilization and cool, cloudy days tend to decrease the demand for water.
One way of conditioning the turfgrass to need less supplemental irrigation or, to remain green between periodic summer rain showers is to tolerate some moisture stress. An observable characteristic of moisture stress in turfgrass is wilt. Wilt is a physiological defense mechanism of the turfgrass plant and allowing some moisture stress actually triggers the plant to initiate rooting, allowing the turfgrass to explore a greater soil volume for water reserves.
Before watering, look for visual symptoms of water stress, such as gray color, leaf cupping/curling, or footprints remaining on the lawn after it has been walked across. Observing some moisture stress within the lawn prior to applying irrigation can be good and improve the sustainability of the grass. Daily irrigation of turfgrass produces short roots incapable of tolerating periodic drought stress. Most established turfgrasses in Georgia only need 1.0 inch of water per week. Irrigation should be applied to supplement rainfall.
Apply enough water to wet the soil to a depth of 5 to 7 inches. Do not apply water until runoff occurs. If water is being applied faster than the soil can absorb it, turn the irrigation off and allow the existing moisture to move into the soil, then apply the remaining irrigation to achieve 1.0 inch.
Pay attention to the weather. Reduce the amount you water when it is raining or cloudy. Avoid irrigation schedules that apply more water than the turf may need. Prior to sunrise is the best time to water because of less wind and lower temperature. Research indicates water loss at night through evaporation may be 50 percent less than during midday irrigation.
Employing some best management practices (BMPs) like tolerating some wilt, allowing water to move into the soil, and not watering during the heat of the day can conserve water and maintain a healthy, attractive lawn.