My typical mix: 40% organic potting soil (any brand should be fine, just should not have ferts in it, ok if it has a little sand in the ingredients) 30% sphagnum moss 20% worm castings 10% perlite
That Fox Farm is great stuff, it has all of what I put in plus bat guano, I think fish emulsion, very rich. Also very expensive, that's why I like to do my own mix.