Keeps it green enough for me for well over a year. Most my neighbors get a friendly dose of it every couple of years and the whole neighborhood perks up from it. I put it down late fall after an aerating every year. I DO NOT use it for commercial customers. I am quite familiar with ag spray but turf is not familiar to me. I limit what I do for spray because so many others simply do it better than I can for less than I would want to charge. I was simply giving you my experience with UAN.