I've used organic compost EKO brand, Bed-a-beast, straight cocoanut fiber with New Zealand sphagnum and leaf litter, "Jungle Mix" (which I believe we decided on another post does contain some very small vermiculite) "organic" potting soil without added fertilizers, vermiculite or Perlite, and all of these have worked well. The cocoanut fiber hasn't much plant nourishment and takes up available nitrogen for some time before it begins to break down. None-the-less, many of the tropical vines and epiphytes seem to do well enough in it. You don't necessarily want to stimulate a lot of luxurious plant growth in a vivarium. Most of the terrarium plants I have do surprisingly well with very low levels of readily available nitrogen and other nutrients. Later of course, they will recycle the frog and insect wastes.
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Patty
Pahsimeroi, Idaho
4 D. auratus blue
5 D. galactonotus pumpkin orange splash back
5 D. imitator
6 D. leucomelas
4 D. pumilio Bastimentos
4 D. fantasticus
4 P. terribilis
4 D. reticulatus
4 D. castaneoticus
2 D. azureus
4 P vittatus