I went through majority of the comments here and it seems to me that for many programmers, their life revolves around side projects and they consider that other programmers should also do the same. There is more to life than just programming. It was not even a job until 100 years ago. Richard Feynman did not only do physics all his life. He learned how to paint, how to play music etc. Why restrict yourself to the programming bubble? The OP seems to me a sane person in this world of overworked zombies with fat bellies who call themselves passionate programmers.
I think this is over engineering. It is cool, but I am not sure if it is practically needed.
1. If you come back home everyday then you can yourself check the watering requirements.
2. If you go out for a couple of weeks, you could ask/get from somewhere the watering requirements of the plant and then give it water at fixed intervals. I think that will work too.
3. The amount of time you spent on doing this, in that time you could honestly learn about watering requirements of plants. And that is something different to know compared to knowing how to write cool code.