An irrigation controller with an embedded web server activates irrigation devices in accordance with an event schedule. The event schedule maybe accessed and modified via a browser-equipped client. In certain embodiments, watering rates and schedules are adjusted in response to sensor inputs. The controller may query specialized network servers such as time servers or weather servers to update the controller clock and/or modify the event schedule. The controller may support multiple protocols such as email, FTP, UDP, HTTP and the like. The controller may be configured as a master or slave controller such that multiple slave controllers may coordinate with a master controller and modify their event schedules in accordance with the master event schedule. The result is an irrigation controller that is easily configured, locally or remotely accessible, responsive to varying weather conditions, and suitable for complex multi zone, multi-system configurations.