Thanks for sharing your experience with bamboo cultivation, Mark. I really appreciate the tips.
Since firsts posting this, I've read more on p. japonica, & several descriptions echo your experience with containment- not especially difficult if you keep an eye on it. I chose this particular bamboo over other arrow-worthy types because it's well suited to this climate, and has a long history of successful cultivation in the U.S.A.
Have not found a supplier of culms from arrow bamboo, so I'll likely purchase Tonkin until my grove starts to produce.
Hope your grove provides you an abundance this summer!