I know the reccomended container mix calls for pine bark fines but when I ask for them at garden centers around my area,central VA Zone 7, they look at me like I'm crazy.
What is a good substitute?
Repti-Bark from Petsmart/Petco is what I use. If you have a lot of potting to do it doesn't make financial sense to use but for me it works well. Some say that the smaller bags contain smaller bark pieces but I haven't had a problem with the large bags.
If you don't wanna go broke, look for pine bark mulch. Pine bark fines does get funny looks, because most people haven't heard of that before. But, pine bark mulch comes in many different sizes, from chunky, regular shredded bark, to double shredded, or even triple shredded. I used to get mine from a nursury, in 2 cubic foot bags, for $5. It was great stuff, mostly fines, with some pieces that were bigger, that I just picked out. Unfortunately, they chose to stock huge flippin nuggets this year. So, I searched the web, and called ALL mulch suppliers who had pine bark mulch and asked about the size. I found one with double shredded, so I went this morning. It was just "ok", with quite a bit of larger, useless stuff, but also a LOT of fines mixed in. I filled two 55 gallon barrels for $12, and simply ran it through 1/2" hardware cloth to sort the fines out. I got about half of it as really nice fines, and the rest is going to be run through my mulching mower when mowing season is over (so I can sharpen the blades in spring). I will then put the shredded stuff in a pile to compost a bit until next year. By the way, it is in a pile right now getting started.
Oh, and a tip, if you choose to go this route, you'll most likely be shoveling out of a large pile. If that's the case, shove the top away, and go for the stuff towards the bottom. Naturally, the rain pushes the finer stuff towards the bottom, and it starts decomposing, making it ideal for what you need.
How close do you live to Virginia Beach? I remember helping someone from there finding suitable bark through my bonsai contacts. If you live near there, I'll figure out how you can get in contact with her.
4-5 hrs from VA beach