Bamboo in Montana?

I know I saw BAMBOO growing in a yard in Helena,Mt. Zone4, years ago.  
So now I'm ready for Bamboo and can not find the yard. Is there anyone who knows anyone growing bamboo in Montana-- borderline zone3, near Helena, 5,000ft.
Or was I just seeing things? Thank you.
I love this place, Renee

Hi Renee,  

There are bamboos that will survive -20 F. Check out the Fargesias I think most of them are clumping bamboos though.   There may be some that survive colder weather but I'm not sure.

Here's a link with some names of bamboos.

bamboo

I'm growing Phyllostachys nuda, a good culinary variety that runs, in zone 5 Maine.  But it seems fairly borderline here.  I know others here in Maine growing yellow groove bamboo, but again I think this is near it's zone limit.  If there's a useful variety that grows in zone 4 I'd love to know about it.

Would Phyllostachys heteroclada Purpurata grow in Missoula?  If so, might this bamboo be used to build to support an earthbag structure, assuming 18' lengths are longer than needed?  I like that it is cold tolerant and has a solid stem.

https://lewisbamboo.com/product/solid-stem/

Did you have luck locating the cold-tolerant bamboo?

I grow bamboo in Great Falls. It dies back every year, I cut down the old growth, and it comes up every spring better and stronger. I have no idea what variety this is