Prune almost to the ground. I would probably leave it until the end of this month before doing so.

I tidy mine up in April

Thanks for your advice about my penstemon. I will wait until the end of the month before pruning.

i would also take a few cuttings just incase you loose it,just snip the tops off and put a few in apot of compost,water in,clear bag over the top to give it a bit of warmth,pot on when rooted,bingo new plants for nothing,i take loads of cuttings every year from mine.

Thanks Plantmaiden. Hadn't thought of that.