This dissertation deals with the design of a completely autonomous electronic transmitting system meant to be applied in plant sensing applications. It is grafted on a previously performed study carried on tobacco plants. It concerned the study of the variation of plant stem's electrical impedance with respect to the drying process and analysis carried to understand which is the best frequency range for signal propagation. It has been found that electrical impedance grows over time if no watering events occur, and it decreases right after the plant gets water. This mechanism offers a considerable possibility: understanding plant health conditions inspecting its impedance by directly exploiting electrical signals propagation inside it.