Grown it and still got it, but only ever in a pot. Self seeds all over the place where happy.

Quite hardy with us at down to -10 at times. As owdboggy says, self seeding can be an issue but fairly easily managed. Wear gloves to grub out unwanted plants in the garden as the leaves are very sticky. In spite of the negatives, it is an attractive plant.

I've had it for several years as well. I think it disappeared for a couple of years, but then reappeared, obviously a seedling. If you tuck it under something else, it should come through all but the hardest winters.

Oh good - thanks, all. I might well plant it out, then. :-))