I bought some regular cactus and palm mix from a big box store. That was 3 years ago, my pachy was 1' tall when I potted it, here it is in July 2014.

{{gwi:2126384}}

Whatever you use make sure it drains fast. Coir and perlite mix should be fine imho.
Evan

I would not use coir but a well-draining mix as Evan has. While it's true there are different substrates for Pachys in their natural environment, I don't think they're fussy about what they grow in when in domestic service. While I've not grown all of them, for me in San Diego I found the old standard 50% Super-Soil/50% pumice worked well. You might have different materials handy, but the excellent drainage is essential.

Evan, when are you going to put that one in the ground? It would go crazy-good in the growth department there.

I've had two that were in the ground that did not do well. I had them in east facing areas and it was just way too hot for them. This one is under a tree in a west facing area and only gets about 5-6 hours of direct sunlight in the summer. It's lasted 3 years like that so I'll just leave it as it is. On another note it was given to me by a dear friend right after my son was born as a gift and if I ever decide to move its coming with me!!!
Evan

Thanks for sharing that. Just one more question: I don't encounter "super soil" brand in my country. What are the mineral components? (such as mica, perlite, pumice and other ingredients)