The hardware is consists of an Arduino microcontroller (here an Arduino Uno R3) and a pre-wired soil moisture sensor module. The soil moisture sensor module , built around the LM393 comparator, gives ...

The Arduino Plant Watering System is designed to automatically supply water to your plant's soil once its moisture level falls below a particular point.

When plants get thirsty, they release a chemical into the soil. That triggers this tech to start releasing water.