I live in Western WA (Seattle area), and I don't think there is anywhere in our state that you can get that species to survive outdoors during the winter. It's only hardy to about 20F, and it will probably experience culm and foliage damage or topkill a few degrees below freezing. I have about 70 varieties of bamboo, and my experience is that most of the tropical clumpers are not suited for our area...I've lost several that were hardier than B. chungii. Although I have a couple of tropical clumpers, they are in pots and go into my heated greenhouse every fall. What you've got is a beautiful bamboo, but you are going to have to move to Louisiana or Florida if you want to grow it outdoors year around.

Many hot climate plants don't like our cool summers, even if their minimum temperature tolerance is comparatively strong.

And there is a difference between a couple sharp nights followed by a return to 70 degrees F. and two weeks of cold that solidly freezes the soil (and roots) to a fair depth.