I’m trying something. I buried a terra cotta pot in my garden because I’ve noticed that the baked clay changes color when it is wet, and it is porous, so if it is wet on one side, it looks wet on the other side. I’m using this feature to tell if the ground is wet in my garden. I tend to overwater, and this might convince me to give the watering a rest.

I’m testing it this summer, and have witnessed the terra cotta indicator as pictured above and all the plant leaves in fully hydrated form, not wilted. I did refrain from watering.