A horticultural system which consists of a container for a plant which sits within a reservoir for irrigation liquid to allow flow of irrigation liquid between the container and reservoir. Irrigation liquid may be to said container and/or said reservoir. Sensor means are located in said reservoir to measure the volume of liquid in said reservoir and a second sensor means in said reservoir measures the electrical conductivity of liquid in said reservoir. A controller is programmed to control the supply of irrigation liquid to the container and/or reservoir using the measurement of liquid height and electrical conductivity in said reservoir. The height sensor consists of a set of electrodes with length equal to the depth to be measured and appropriate electronic circuitry for measuring conductivity between said electrodes and the electrical conductivity sensor consists of a second set of electrodes of short length relative to said first set of electrodes with appropriate electronic circuitry for measuring conductivity between said electrodes.
