Mexican Pinguicula can be grown in an extremely large variety of media. Mixing and matching media ingredients to make your own preferred combination is part of the fun of growing these attractive little plants. I've grown them successfully in various combinations of -- peat moss, perlite, charcoal, pumice, vermiculite, coral, gypsum, LF sphagnum moss, silica sand, aragonite, ground fir bark, and small aquarium gravel. I'm sure I overlooked several other media ingredients -- they are very adaptable. Especially when growing them in an all-mineral media, it is suggested to feed them just a little, periodically.