Cool project. I'm doing something similar with Adafruit Feathers transmitting over LoRa, integrated with Home Assistant. My focus right now is measuring compost pile temperature to optimize the process. Currently trying to reduce power usage for longer life on battery.
What kind of moisture sensor are you using? How well does it work for you? Adafruit soil sensors have been disappointing so far, but I have a new model called Chirp that looks promising.