Because the program’s end time has to be prior to start time, what you need to do is to split the program to two the first program will start somewhere before midnight (say 9pm), and end at 11:59pm. The second program will start at 00:00am (or perhaps later if you don’t want it to start right at 00:00), and end at, say 6am. Both programs will be set to water the selected station(s) for 15 minutes, and repeat every hour. This should achieve what you need.