I make up two mixes for aroids and other plants - they are as follows:
Alocasia and Philodendron:
4:3:2 mix, by volume, of, composted pine bark (Fafard organic soil conditioner), washed coarse Perlite, and ProMix BX or ProMix HP. I use a large metal feed scoop to add the ingredients to an electric concrete mixer that has never been used for anything but soil mixing. So it is 4 scoops composted pine bark, 3 scoops washed Perlite and 2 scoops ProMix. As it is mixing, I add in 2 cups of Nutricote 18-6-8 180 day formulation.
Other plants (including aroids that don't mind being moister):
1:1:1 mix, by volume, of composted pine bark, washed coarse Perlite, and ProMix (3 large scoops each of the three ingredients). Same fertilizer supplementation as above.
The Nutricote takes a week or two to kick in so in the meantime, I may add regular Miracle Gro solution at 1 TSP per 5 gallons, several times per week. First fert after potting is Miracle Gro Bloom Booster at same concentration as above, to enhance root development. This is for summertime growing - in winter I may not use the Miracle Gro, or use it only if the weather is warmer over a longer period.
LariAnn