If you are conscientious about root pruning, you should have no problems. I have been in my present location for 3-1/2 years, Zone 8. I have several clumps of Black bamboo in full sun that started as 5-gallon pots, and each clump now occupies a space about 3' in diameter. Black bamboo can be aggressive. I have had runners go as far as 6-7' in one season, but they are pretty close to the surface and not hard to tame. I typically go down a couple of inches, find the runner, cut through it with a long-handled lopping pruner, and then pull it out of the ground. It will take a little strength sometimes and you will be pulling dirt out that you will want to knock off. If the rhizome is too hard to "unzip" from the ground, I've found that slipping the pick end of a pickaxe under the rhizome and leveraging it will usually get it unstuck.

kudzu9,

Three-feet in diameter after 3-1/2 years? Perhaps it's because of the plants getting full sun.

I've had a P nigra, originally a three-gallon plant, in the ground for three summers, now, and at its maximum the grove is about 20 feet across. Had I not pruned its rhizomes last fall, I'm sure it would have gone even further. The site gets maybe half-sun, if not a little more, and the plant seems determined to run where there's more sunlight, or so it seems.

Potentially, if ikea_gw's experience is similar to mine and doesn't root prune, P nigra could be outside of a 30x30 area in under four years.

Well, all I can say is that Ph. nigra's preferred growing condition is full sun, and my soil is good, so I think that the annual root pruning is what keeps it tamed. If you didn't know better you might look at it and think it's a clumper because it's put up plenty of shoots in a tight circle. If I didn't root prune, it might be halfway around the block by now!