I've got three pretty big clumps of red hot pokers, one of which is the white variety with very large long leaves. I leave them all alone during the winter and trim them up in the spring to get rid of dead or broken leaves. No worries.

I cut mine back hard to get a tidy clump, like pampas grass. In Spring they simply shoot up fresh new foliage and bloom normally.

happy hibernating

Here in Oklahoma it gets very cold in winter. I leave all the foliage on the Kniphofia until Spring warm-up and I see new growth coming out. The old foliage does get to looking a little droopy, but it protects the plants from the bitter cold (helps insulate). I do this with daylilies and ornamental grasses, too.
~Annie