Hi Al,
Been following this thread and enjoying it. However, I'm curious did you have a change of heart about air pruning roots?
Not sure yet.
In 2000, Fred Miyahara from San Diego brought over Tomohiro Masumi of
Koju-en shohin nursery and he traveled California. Tomohiro is well known for his driftwood style shimpaku's and also his deciduous trees. During his travel here and thru the translator he talked of developing material in colanders. While I have no idea how long they had been useing them in Japan it was new business here in the states. After his visit everyone clamored for anything that would work as a basket. Pond baskets 10 years ago were around but were very expensive. Dollar stores were not very plentiful either guiding the way with cheap colanders. I did buy a few and while I was privy to the ways of Jim Gremels yamadori style juniper design, all of my tries had died slow deaths. I think mostly I had seperated the cambium from the trunk and killed the tree.
While most that do this type of thing may bend and twist hundreds of plants, I was only doing one or two. My ratio was not to good. Even if I had a 50 percent live ratio, 50 would be better than one. The rage of course was to plant them out in the colander and expect this huge growth spurt in mathchstick twisted cutting to driftwood masterpiece in 5 years. Hah! I didn't even get one to live. I do remember from my experiences with colanders, at least the cheap ones from the dollar store, that they broke down pretty fast in the sun and would crumble when tried to be picked up.
During this time my desire to grow diciduous trees was not very well developed. I was still a juniper lover and thought that junipers were Gods gift to bonsai. It was not untill 2001 that I would embark on a love of trident maple that would forever keep me in the ranks of decidophile forever. Not to mention hackberry, elm, hornbeam and many others.
When I embarked on this journey to own and also create my own fat trident, it never occured to me to grow it in a colander. I had so much success so fast that I couldn't see why I would need to go back to a method that didn't seem to add any improvement.
So in an effort to be fair I am trying a couple this time around to see what results I get. I know what can be expected in three to four years growth without them and am looking forward to even faster growth with the aforementioned "holy"grail of bonsai growing. ( pun intended )
I am an advocate of corase soil mix for increased air circulation around the root hairs. If this air layer works like it should it should be a supercharger to root growth with my coarse soil.
Time will tell, Al