Have never had much luck lifting evergreen grasses.....and have not attempted growing this in a giant container (it really is a big plant)
How about the tall New Zealand red-tussock grass - chionochloa rubra - another evergreen but has much better hardiness for your zone....and a gorgeous plant which has everything the giant oats has, especially when back-lit.

yes, i know it gets v. big for you, but i doubt it would here.

camp, you do know that British (and PNW) gardeners garden in Paradise, yes? Things grow quite differently here on Earth for us z.5 New Engand gardeners... (btw, the chionochloa is o.k. but it's those stipa seed heads that have me lusting......)

I meant to say that things grow quite differently here on Earth for us mortals in z.5 New Engand . :-)