never grown it, but most herbaceous perennials should be cut to the ground in spring, and I'd be inclined to do that now with these, unless you don't mind the way they look.

These died back down completely in the winter Bamboo, this is all new growth, would you still cut them back ?

Yes I would, but then I'm just ruthless like that - if they don't perform well, they get a cut as a second chance!

its the 'chelsea chop' Louise.

Ah, is that what that means, Seaburngirl, I keep hearing that phrase - I've obviously been doing it for years, lol!

Won't this mean that i lose all the flowers that are to come though ?

They'll come through later, admittedly, but if you're anxious about doing it, leave them alone.