Paul - Dream on.....
Seriously they're only hardy to about -5c and probably less in pots. I have seen them killed outright in Seattle but those up against the hotel were just singed.
I have an inordinate passion for them and grow them in pots=tubs=bigger tubs. They grow like hell, problem is like bamboo they quickly exhaust the soil and get potbound and so you either have to divide them often or pot on. If you pot on eventually it gets impossible to lift and lug them indoors in late November. They're heavy drinkers in the growing season but must be kept quite dry in winter. Nice thing is they never break in the wind and have seen them near Peggy's Cove tall and straight as a poker and you know how the wind blows there.
Phormium 'Amazing Red'
Phormium 'Dark Delight'
Phormium 'Dusky Chief'
Phormium 'Guardsman'
Phormium 'Jack Spratt'
Phormium 'Maori Sunrise'
Phormium 'Sea Jade'
Phormium species unknown
Phormium 'Sundowner'
Phormium 'Tricolor'
Phormium tenax
Phormium 'Tiny Tiger'
Phormium tenax 'Surfer'
Phormium 'Yellow Wave'
If you're ever down here and need divisions we have the above. Most came from Cistus in Portland or The Plant Farm. I'll take a few pix.
johnw +21c - send some rain please.