ABSTRACT: In Iceland there is a super abundance of waste hot water from geothermal power plants at a temperature between 130-160°C. Some of this is re-purposed to heat cold water and is used for district heating and heated swimming pools. This waste energy source has also enabled the growth of out of zone plants, enhanced agricultural production by 20%, and extended the growing season by using the authors’ energy intensive shallow system of bottom heat that incorporates existing heated sidewalk technology. Complete autonomy of the field tested heated garden system is not possible without an independent, sustainably powered irrigation control system. Long term plant studies on the plant growth have been limited due to the lack of scheduled and reliable watering cycle as plants die during the growing season. The authors have also designed and constructed an automated thermoelectric powered irrigation system that was developed for the maximum plant growth of the Icelandic heated gardens. It has a subsystem that records soil moisture and ambient temperature. When the soil is too dry it is irrigated by opening a valve connected to a municipal water line. An identical irrigation system is currently in use for the author’s heated green roof experiments at The Cooper Union in New York City that uses waste heat from a Combined Heat and Power (CHP) system as the heat source. The system allows for long term maximum growth experiments while increasing the system’s sustainability.