When a metal electrode is inserted into a part of a plant, and another metal electrode is placed in the soil, an electrical potential difference is generated between the two electrodes. The plant has a lower potential than the soil. The generated voltage from the electrical potential difference between one plant and the adjacent soil is small (several hundred millivolts), and the current is extremely low (several hundred nanoamperes). However, in order to boot up some electrical circuits, the voltage and current need to be in the volt and microampere order, respectively. If the electrical potential difference between one plant and the soil is used as a power supply, it is necessary to develop a nanoscale electrical device that can work with extremely low wattage. Here we report a novel green battery composed of 10 pot plants by serial–parallel connections. The developed battery could generate almost 3 V and 3 µA to drive electric devices. We designed an LED blinking circuit composed of discrete semiconductor parts, which was driven by the generated plant power, and confirmed its performance through the experiments. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.