I've been looking around for epiphytic utrics for a while now. Epiphytic utrics are apparently difficult to grow. In the wild they grow on mossy rock faces with “bare peat and sphagnum” , shaded by trunks and branches. Water dries up really fast in their habitat, so they rot if kept constantly wet. These Utrics also require low temps 60.8 - 78.8 degrees Fahrenheit.
U. Humboldtii may have warmer conditions.
In the wild, the species (Asplundii, Jamesoniana, alpina, campbelliana, and quelchii) grow in small amounts of substrate, and they must be able to dry out slightly.
In the wild, the plants go dormant in the summer, produce flowers in the winter. Keep watered in the winter, barely water in the summer, so that it’s barely moist.
I found several sites mentioning a "Oreo Cookie Method" -- basically lots of perlite sandwiched in between two relatively thin layers of sphagnum.
Some say to grow U. Humboldtii in coarse peat, in plastic pots sitting in shallow water.
A site said to grow U. Humboldtii in 50:50 peat perlite.
Another site said to grow all utrics in dried LFS, perlite and lava rock pieces, or just to use Nepenthes soil mix containing orchid bark and peat.
Another post on this forum recommended to use peat and coco-fiber for the Humboldtii
Every other "macro" utricularia is to be grown in mostly in LFS though some of the larger pots have a core of coco-chips. (Thanks Rattler mt!!!)
Some people who have grown their plants submerged in water have decided that it causes their plants to rot away.
Many of the sites recommmended just watering from above keeping the plants' soil barely wet.
If any of you have corrections or more to say please post here. I'm planning to get some soon, so I'd like to know any info that might help. Thanks