I don't know 'Triumphant Blue', but deciduous types are supposed to be hardier than evergreen ones. You can get them in different sizes too, Peter Pan is one shorter one that I have. I'm in the Pennines too, west but quite high up. Last year I planted mine in the border and they did well and looked wonderful, but I shall continue to lift them with the dahlias, as it can get very cold here in the winter. Just don't talk about the wet
Bob Brown at Cotswold garden flowers has a good range and gives his own tried and tested hardiness ratings, on clay in the chily Cotswolds. I got some of mine at plant fairs and the rest (good plants too!) at B&Q. My Midnight Star/ Navy Blue set seed and I am currently growing on a whole load of little plants. May have enough soon to experiment
They have a huge line of them at Floors Castle (South scotland), so the only thing in a border that you look across to something else (if that makes sense). Looks fabby. Full sun but well sheltered.
I have a large bed of variegated ones that have been in for around 3 years and look great as the leaves give interest when the flowers have finished.
I always bring mine into the greenhouse for winter.
Hostas are beautiful though, he works very hard in his garden.
aw shucks Lyn. You'll make me blush.
Mine are happy in a border.
I think I try a pot behind kniphofia tawny king instead of planting into the border. I like a quite tall one , northern star and jacks blue look like good candidates . When eventually it out grows its pot, I can try planting it in a border then if I wish.