An interface system 11 for an irrigation controller arranged to operate a plurality of electrically operated valves 21 over at least two wires is disclosed. The system includes a valve interface unit 27 having outputs 29, each for connection to a valve, and input 33 and common 35 connectors to connect to a feed wire 23 and a return wire remotely from the irrigation controller. The system has a user programmable input 49, 51, 53, 55 interfaced within a controller 41 to set the allocation time for power to provided sequentially to the outputs 29 to power the valves.
