I didn't have much time this weekend, but I managed to draw some schematics. I only used Eagle CAD for my electronics projects before. This time however I decided to give KiCad a try. This is how it went:

I didn't do as much progress as I hoped, but it is a start. The schematic is missing the humidity sensors as I didn't test it. This is probably the next thing I will try. As for the buttons, I don't know how many free pins will I have, so that has to wait too.

This is all for this update, I hope by 22nd August I'll have a working prototype.