Red Hot Pokers.

i would try now? Mine have just finished flowering, and ground is not too cold yet either.

Some say spring others say spring and autumn I did mine a couple of weeks ago, but if autumn you need to do before frosts I would have thought.

Personally I would leave it until spring but I'm willing to be proved wrong by someone who has successfuly done it in the autumn

I agree with Andrew about spring. I did some in autumn afew years ago and they sulked and took months to recover.