With the bags the roots poke through the fibers which then constrict the outside of the roots, resulting in a sort of half-root going out into the soil. So nutrients and water are gotten from the soil but it is still possible to dig the tree up later. How thick the roots are when they encounter the fiber should have no bearing.

A friend once grew eucalyptus in root bags and they grew these hilarious stub roots inside the bags that looked like fingers. The parts that extended beyond the container walls were like hairs.

Independent garden centers here received assorted collector type trees including Ashe magnolia and other magnolias, Chilean fire tree etc. this week from a source that delivered them still in the root bags they were grown in.

This post was edited by bboy on Fri, Mar 7, 14 at 12:05

I've read that the "stubs" left after tearing the bag off are poised to easily regenerate roots from the calloused ends. I wonder how well that works in real life. I would imagine at least as well as from cut ends of a B&B tree that is dug the "old" way.