Attila

I agree with Rockm. I've been growing trees in the field for 15 years, and comparing them is like the story of "The tortoise and the hare" - except the ending. But the pitfall is that you can also end up like the hare, if you don't know what you are doing.

But field-grown trees grow incomparably faster. I have a trident maple that has a 5-inch diameter lower trunk. It took only 3.5 years from a cutting. The ones in pots are 0.75 inch, the same age. This is over 44 times faster, if we compare the area of the circle created by the base of the trunk.

I used to think that planting the tree in a large pot can create the same condition as field growing. Big mistake: growing in oversized pot creates waterlogged conditions, and the result is even worse then growing in a smaller pot. So the pot can be only slightly larger than the rootball, but not too much larger.

There is one way that you can improve speed while growing in pot: each year you plant the tree in a slightly larger pot, while doing a little root pruning. This way you don't overpot, but provide more room for the growing tree.

The only species where I didn't see much difference between growing in the ground or in nursery pot, are the japanese quince cultivars. Growing these in the ground did not result in large trunks, but rather produced suckers all over the place. In nursery pots, these suckers at least are close to the central trunk, so with time they can fuse together creating a turtle-shell like nebari. In the ground, they are too disbursed. I have one fast-growing flowering quince which benefited from field-growing, it is commonly called "winter-quince". This has a more upright, tree-like growing habit.