My growing guru, Jorge Cervantes, advises that best time to water is just as the lights come on. The only thing I do different is to make sure I water a couple hors before harvesting. I've done a lot of experimenting and found that the nugs are juiciest 2-3 hours after being watered. So if I'm going to harvest a plant at 5 PM I won't water that one until 2 or 3 PM. Works for me. BigSteve.