I too am very interested in the mix. A little forum search returns the formula:

- 5 part mini pine bark nuggets
- 1 part perlite
- 1 part peat moss

From online research I see people comparing 5:1:1 mix with "Pro-Mix" (commercially available, premixed by the vender).

I am also curious why people find 5:1:1 mix effective. My guess is that this mix offers a high ratio of air gaps, ideal for aeration and drainage. But the above materials seems to be extremely nutrition poor, so the grower has to fertilize well for the plant to thrive.

Daniel, from what I've read, I gather they fertilize (in dilution) more often than normal and the pine bark is what holds all the nutrients from the fertilizing.