An expandable irrigation controller for controlling a plurality of watering stations in an irrigation system includes a removable front panel and an inner housing, connected to the front panel. The removable front panel includes a plurality of manual controls operable to input instructions for a watering program, a memory operable to store the input instructions and a controller operable to execute the watering program. The inner housing includes a circuit board including control connectors which are connected electrically to the controller and a station module operable to provide an ON/OFF signal to at least one watering station of the irrigation system. The station module is electrically connected to the circuit board via the control connectors and the ON/OFF signal is provided based on instructions from the controller in accordance with the watering program. The control connectors are positioned in a substantially continuous line extending across the inner housing such that the station module is connectable to the control connectors at substantially any desired location. Multiple modules of different sizes may be mounted in the inner housing as desired. Control information may be provided via a radio frequency supply and received by a radio frequency module to be provided to the station modules and to external station modules in an external housing.