Abstract: An irrigation system having an irrigation controller, a means for detecting changes in environmental conditions, a valve, and a sprinkler connected to a irrigation supply. The controller controls the operation of the valve and the sprinkler in accordance with an irrigation schedule to selectively irrigate a specified number of vegetation areas. The irrigation schedule is adjusted automatically in response to changing environmental conditions. The irrigation schedule is created based on a number of input parameters including the number of cycles to be executed each day, the duration of each cycle, and the number of days in the irrigation period. After receiving the appropriate input parameters, the controller then automatically determines the days within the irrigation period on which irrigation should occur.