Programming a controller is easy. You just need to program the current day and time and you are ready to create a program for your zones or stations. It only takes three ingredients to complete a program: a start time, run times, and days to water. A program is a group of stations that share the same schedule: same days to water and same number of times per watering day. You only need one program (Program A) if you want all your zones to water on the same days and in a sequential order. If some of your plants or lawn areas have different watering needs, they will need to be put in a separate program (Program B and/or C).