John, I suspect that this soil worked well for the man who owned them, because he lived in a far wetter area, and only moved here recently. However, there was not as much root growth as you would expect to see. The Japanese maples had very few roots considering how long they had been in their pots. And the rocks and pebbles were primarly smooth, not pumice or lava or akadama.
This was the extreme of what I have seen. Unless these trees were regularly dosed with fertilizers, there was nothing to hold the nutrients for the roots. And I suspect that they weren't dosed with fertilizers often enough.
But I'm not going to argue with you guys.
Joanie