Posted: 11/03/2016 at 23:33
Thanks everyone! Much as I suspected. I put them outside today as it was quite warm and sunny here in the South - I brought them in at night. I will see if I can find something amongst my garage junk to make a cold frame!
By the way - the rose is bare rooted and coated with a waxy substance. It has quite a few tiny buds forming. I understand roses are tougher than most other plants so maybe it can go out in a week or so?
Judith - I am not planning to put the Montana round the arch (that is for climbing roses.) I have grown them before, in my previous garden. I want it to cover an ugly wall and then grow along the adjoining fence/hedge. There is plenty of room for it to do it's thing!
Thanks for the kind comments re garden structure - it was previously the ugliest garden I have ever seen - all concrete and red paint. See 'before' photos. (I have painted the red wall to look like old bricks.)