Let me get this straight ... You've had a Hedychium in a 14" pot for 3 years? No wonder the pot is full of rhizomes! Have you ever divided it? Hedychium are very easy to divide and (as you probably know) very fast growers.

We grow ours in part shade to almost full sun.

Given your zone, you could probably divide it any time. We're in a similar zone, and we divide ours whenever they look like they need it.

Start by dumping everything out of the pot. Then get as much dirt off as you can so that you can (1) see the rhizome structure, and (2) untangle the fiberous roots as you make your divisions. It will be obvious where to make your cuts. A sharp knife should do the job. Try to divide into clumps of 2-3 "stalks". You will probably also see new shoots starting from the rhizomes. They will appear as little pinky-white nubs. Make sure there are some of those on each clump when you make your cuts. If you end up with a rhizome with no stalk, that's OK. Just put it into it's own pot and cover under about 1/2" of soil. It will start to show signs of growth in a couple of weeks.

If you're not sure where to make your cuts (if the rhizomes are just so intertwined) just cut anywhere. We had one container that was so jam packed that I had no choice but to cut it down the middle and then lop of pieces ever couple of inches. From that one pot we now have 8 5-gallon containers that are almost ready to divide. And it only took 6 months!

As for soil, we use a soil-less "pro-mix" type of medium. We fertilize with 20-20-20 and vitamin B1 on a weekly basis. We keep our new divisions in light shade for a couple of weeks until they start to perk back up. Also, keep the medium moist but not wet. You don't want to risk rotting the rhizomes.

Be prepared that some of the existing stalks may lose leaves or die back totally. That's OK. As long as there are some new growing eyes you'll be in good shape. And in the end you'll have divisions to trade with people!