I'm not much of a gardener but the idea of measuring the moisture level seems ill-conceived... Namely because you are measuring at only a single point in your 3D region of soil, and you don't know what range of moisture should be maintained without experimentation.
Using our guy's own sawtooth model of watering/drainage, it would make more sense to just water at fixed intervals and experiment with the frequency to see if the plant grows.
As the plant grows the rate of water being removed from the soil increases, so the amount of water supplied will need to increase. Varience in illumination, temp, and humidity will also change transpiration rates.
Using our guy's own sawtooth model of watering/drainage, it would make more sense to just water at fixed intervals and experiment with the frequency to see if the plant grows.
Still a fun project!