One other question, CPgardener, if I may:
You say a tree's roots in a container will grow to the point where "... there will be too many roots and not enough soil ..." I have heard that from other sources, too; that over time the soil in a container will disappear.
What actually, physically, happens to the soil matter? Does the tree incorporate it into its own tissue? Do soil organisms metabolize it away? How can soil disappear like that?
PotterK
