Abstract: A system is described for monitoring moisture level in soil and controlling the application of water to the soil or other growing media. The system includes at least one sensing unit which is disposed in the soil and is adapted to periodically monitor moisture content in the soil. The sensing unit is powered by low voltage, low current, alternating current having a frequency in the range of 1.0 to 10 KHz and utilizes a square wave with fifty percent duty cycle. A control means is electrically connected to the sensing unit and is adapted to (a) compare the moisture content in the soil to a preset moisture requirement, and (b) control the application of water to the soil.