Well I wouldn't risk it, especially where you are, unless you're right on the coast. I used to live in Kent and it gets surprisingly cold in winter at times, and when they're very small, Penstemon aren't the hardiest of plants. You could buy now and pot them up, keep them in a greenhouse over winter, or somewhere frost free but not too warm. If we knew we were going to have a long indian summer, right up to the end of October, then that'd be different - but we never do know, do we!

Thanks bamboo take the point about indian summer if only we could predict.

I agree with Bamboo, I purchased some Penstemen plants from a well-known mail order supplier but lost some of them over the first winter. Some of the varieties are hardy but some not so much.

Thanks for that Jimmytheone I will wait until next year before I purchase.