When is The Best Time to Water The Turf? May 20, 2014

From strictly the standpoint of what is good for the turfgrass plant, water should be applied during the day, preferably during the morning. Doing so reduces the amount of time the leaf remains wet which reduces disease incidence. While some water can be applied during the day without too much inconvenience to golfers, it is impractical to water the entire course during play. Well-designed irrigation systems make is possible to precisely apply water at night which can have the added advantage of capitalizing on lower energy rates charged at night, which saves the course money.

More from the USGA