Can lycianthus rantonnei bush be planted in a pot outdoors?

We are in Straubing, Bavaria, Germany and have seen many of these in very large pots (3 to 5 feet in diameter with many flowers planted around the base) on the streets. I don't think they move them in winter but can't be sure. They are beautiful and would appear to be very old. The "trunk" (because of the way they are pruned) of many would be about 1 1/2 inches in diameter and long-healed pruning marks are abundant. We saw these being watered by a city truck but I can't tell you how often this happens. I am trying to track down a source for this plant in the states because I want to grow one but have had no luck with the major nurseries. Can anyone help with that?