If your tree has been in the same pot for 8 years, or only been potted up (as opposed to being repotted, which includes bare-rooting, root pruning, and a change of soil) It will definitely need better care than removing the soil/root mass from the pot and dropping it in a planting hole. It will need bare-rooting and correction of all problem roots before being planted out.
The existing soil/root mass will look much like a tangled ball of yarn, with plenty of encircling/ girdling/ crossing roots, as well as roots growing straight up, down, or back toward the center of the root mass. All the aforementioned should be corrected lest your tree ends up looking like these after a few years:
Your tree probably looks something like this ^^^ currently
This tree ^^^ 'strangled' by encircling/girdling roots.
Al
