I use the standard ABG mix on a false bottom set up.
2 parts milled sphagnum moss
2 parts fine tree fern root (ground TFR)
2 parts fine orchid bark (smallest size, i'm using coco husks for this next time)
1 part peat moss
1 part charcoal (not sure if it's activated or not)
I've grown EVERYTHING in this. When I rotate it out of my tanks (after a couple years) it goes in to my flower pots.
My husband developed a mixture that is working really well. We do the bottom layers in Geolite now since it is so much lighter and it is easy to suck out extra water from the bottom when cleaning. But on top of this we did a mixture of Flourite (a laterite aquarium substrate), pearlite, vermiculite, and a little pea gravel. We set up several different vivarium at the same time, and the plants are much nicer in this one. There is spagnum moss and live moss on top of this layer. We are using only normal flourescent lighting (4x48 watts) and the plants are flourishing, including peperomias and cryptanthus. It doesn't get all soupy like when you use a soil type substrate and provides better drainage.