This paper describes the principles of automating the Maitake (Grifola frondosa Dicks. Fr.S. F. Gray) mushroom's cultivation process using the developed speaking mushroom approach (SMA) system. The system measures the bioelectric potential signal from the mushrooms and uses it as a control parameter for the lighting conditions. The purpose of the SMA system is to allow optimal control over the cultivation environment in order to improve the running cost and production yields within mushroom factories. It uses sensors and actuators to maintain the optimal temperature and humidity, and uses the known inherent mushroom bioelectric potential to control the lights. The results from the SMA system in this experiment showed a clear bioelectric potential present in the Maitake fruit body. These bioelectric potential signals reflect the internal rhythm of the mushroom as well as external stimulations. Analysing the measured signals the SMA system demonstrated that it will be possible to save energy and time during mushroom cultivation.