Hi Bathgate, I have a similar one called blue candles.
I leave the dead flower spikes on as winter protection and they do look pretty frosted. I remove old growth in March and new growth comes from soil level. if its been mild there are usually 1-2" high shoots that I don't cut down. I don't find it invasive at all. its a very compact herbaceous perennial but it does get bigger in time. the original one was 3" in diameter after 4 years it is about 5" in diameter. So yes it does 'spread' but doesn't run.

hope this helps

It does help a lot. Thanks SBG

This looks wonderful! Is it good for bees and butterflies? I know most flowering things are, but some are more of a magnet that others, and it's magnets I'm after!

yes it offers lots of nectar. hoverflies love it in my garden.

Pennyfarthing, SBG is right. Butterflies & bees are all over this. I get the occasional hummingbird. Looks stunning in a floral display - comes in pink & white as well.

Love it! Definitely buying one. Humming birds! If only!!! But I'll be content with bees and butterflies.