Lady i think u hit the nail on the head. see there in a plastic bin which is in another one with a couple blocks of wood to keep it from being right on the other bin and not letting water drain. and last time i watered it came out of whare the 2 bins meet. so i guess there drowning in there!

and they get watered all around it might just be some of the top dirt dries faster then the rest due to shade and light?