Here is a tested Arduino project that uses 3 sensor probes as water level indicator with 3 leds and one LCD display + a simple controller that turns on a motor when the water has reached the desired ...

However, since different plants require different amounts of water, you're free to modify the Arduino code's thresholds to suit your specific plant.

I've got an Arduino/Bluetooth (Bluetooth Bee-Standalone). I've hooked it up with an HC-SR04, it's intended to be mounted at the top of a rain barrel to measure the water depth. What's the best ...