I’m constantly scouring other peoples projects looking for ideas. Devon’s PiPlanter – A Plant Growth Automator project cleverly uses nails and the conductivity of water within the soil to measure soil moisture.
I’ll have to give this a try with the soil in our terracotta pot. We’re finding that the wild flowers we planted are very sensitive to low moisture. For example, we’ve had rain nearly a week straight until 2 days ago. Last night we noticed that the flowers were drooping already! A few pints of water and an hour later they were back to full strength.