Hello all,

I have been a "silent" but very active board member for some time and have read every post I can find on both gritty mix and 5-1-1 mix. Al has generously helped me with my own 511 off-board, but I still have questions. Rather than drive Al nuts with more emails, I thought I'd post it here.

I've been transferring my plants over to the 511 mix with success. I use reptibark, regular perlite (strained, rinsed), and miracle-gro potting soil. The latter I reduce to about half of what the recipe calls for, though lately I've found that keeping it at the right volume works better with plants with shallow or fine roots.

What I don't understand, and this is hard to explain, is how the 511 actually works. By this I mean, I don't quite understand the fundamental principals, at a kindergarten level, of the 511 mix. For instance, I don't understand the logic of the mix and how it differs from just adding bark to regular potting soil. I don't understand what purpose the perlite is really serving. I just know it works if I follow the instructions.

However, this lack of understanding makes it difficult for me to know how to customize the mix for different plants. More than this, I just want a better basic understanding of the mix at a super basic level.

I would be very grateful if someone could address any part of this question. Thank you so much!