One of my favorite questions. Must be, I've been asking it for years. Here's what I finally found:
My current source: Red Dome: http://www.reddome.com/index.html
I like them because the lava rock is BLACK! The downside is the price. I can't resell it at a profit. I use it only for my personal trees.
I found another supplier of black lava rock but they only sell by the TRAIN CAR load.
My former source: A local nursery will order "Colorado Soil Conditioner" from Gonzalez Supply in Pensacola. That lava rock is a dark red. Gonzales Supply gets it from Colorado Lava: http://www.coloradolava.com/
. I'd order it from Colorado Lava, but their prices are
"FOB" (freight on board). I'd have to arrange the freight transport myself.
I did find a company on the web that would ship to a reseller in Louisiana, but when I asked them about it, they told me the product had been discontinued.
Now that I've finally got a business license to sell my soil, I'm thinking about making a trip to Pensacola to pick up a pallet of the Colorado Soil Conditioner. They only sell wholesale to businesses. I'm thinking of making a lava rock/haydite soil mix.