Well if you don't do anything you are going to loose it anyway as it will choke itself.

What I would do?

Let it set in the pot till fall and supply its needs till it hardens off.

Late Sept to mid October...now the scary part.

Remove it from the pot and proceed.

I would hose flush all dirt compost or whatever it is growing in away. With that done cut away all J roots along with all others that could be potential problems. Make sure you keep the root mass wet while surgery is being preformed. Don't let it dry out.

Save the roots that have potential especially those that have the fine hair like threads attached to hardened off wood. They will feed the plant while it is reestablishing new roots.

Build a mound to set the plant on with root flare 2 inches above grade. Spread remaining roots out into a flare and lightly pack in the dirt in and around making sure you sight it in for level at the same time.

Stake it for a time. No amendments, watch your water. It should be OK.

Dave

This post was edited by Davesconifers on Mon, Aug 18, 14 at 15:48

Dave's advice is very good, however I would add this. I had a couple Abies firma a few years ago that were incredibly root bound too. In addition to cutting, you can select a few roots and depending on their degree of brittleness, unfurl them, so to speak. In my case, for each plant I was able to pull out a couple roots and give them a radial run over 3' away from the trunk. I placed them 180ð from one another. This will help both with anchoring and exposing it to a larger soil area with more material from which to draw water and nutrients. Maybe not all roots will be as flexible as those Abies roots were, though. They were 1/2" thick and I was still able to do that.

They established very quickly and both are now growing about 3' a year w/o any fertilization.

This post was edited by davidrt28 on Tue, Aug 19, 14 at 5:13

In addition to what Dave said, also see the reply from gardener365 on my similar post last year. link to old post
I got very detailed instructions from these two and helpful hints and encouragement from many nice people on the forum.
I'll tell you it took me several hours to do the first one, and I had a backache afterwards from bending over. But once I had the experience with the first one, the others went a lot quicker. Working on an elevated surface helps. Don't be afraid to get a little rough if being gentle is not getting results, that is, the roots are too tightly wound up.

This post was edited by wannabeGardnr on Tue, Aug 19, 14 at 12:16

I had a backache afterwards from bending over.

===>>>

turn over a 5 gallon bucket.. AND SIT WHILE YOU DO IT ...

in fact.. you can probably use the pot it came in ... at this size... they should support your weight ...

really now.. you are going to be filthy by the time you are done.. so go all in ... lol

you bought a bargain ... and now you are going to pay the price ...

when .. in time.. your time becomes more valuable... then you mail order a smaller plant ... that is not such a nightmare ... its the cost/benefit ratio ...

ken

If you sit on the bucket, Ken, and your tree is resting on its side on the ground, and you are trying to untangle and straighten the roots, you are having to bend down, thus, backache.

Putting the tree up on a table and working standing up worked much better for me. Could be different for different people.