An automated irrigation system was developed to optimize water usage for agricultural crops. The system has a distributed wireless network of soil moisture, humidity and temperature sensors placed in the root zone of plants. A central control unit handles sensor information, triggers actuators and transmit data on the internet so the user can monitor the field in real time from any remote location. An algorithm was developed depending on the threshold values of the soil moisture, humidity and temperature and is programmed into the central control unit to control the quantity of water fed to the field for irrigation. The whole system is powered by solar energy. Sensing unit and central control unit are connected with each other via a wireless link. Because of low energy consumption, low cost, and energy autonomy, the system have potential to be useful in water-limited geographically isolated areas.