There is a tree grower near me that is using what they call the "pot in a pot" method of growing trees for sale. They have a large bed of gravel with pots sunk in it. They then put a potted tree about the size of a pencil in that pot, hook up drip irrigation w/fertilzer and the trees grow like crazy. The man working there said the trees that were 3"-4" caliper were only 3 years old. These were Cleveland Pears, Various Oaks and Maples. The poplars and River Birch were even larger. They were selling them for about $80 each. When someone wanted to buy one they just pulled the grown tree out and replaced it with another potted sapling.
