on topic of substrate use.. im only going into my 2nd yr using a very porus potting mix..
but the results ive had with my titanums, konjac, various amorph species.. has been good...
the root systems on the corms has been outstanding.. i attribute shared success to the potting mix,
and my ingredients used when watering..
my potting mix i make my own.. roughly
60% pine bark chunks ( around 3/4 to 1 inch (2 cm)) in size
30 % similar sized pumice
i try to get most of the pine dust out of the bark before i mix for potting
watering..i always fertilize when i water
im "thinking" my fantastic root growth is from the good drainage (yes i water more)
and from using kelp,fulvic,humic acid powders..along with biological fungicide
i was concerned using this very porus potting mix with..especially the tropical amorphs.. thinking
the pots would dry out to much..and theses tropicals prerfering a more "moist" potting mix..
but i have found the roots fine.. with many clumps of root hairs off the main roots..
nice and firm white..and "furry" with root hairs.. LOL

would love to hear what u all find most successful..and experimenting with..
??? much thanks...