I read that these should be repotted in spring. However mine really needs dividing yesterday.
What is best to wait or do it asap?
Uninformed reply is to do it now as it clearly needs it, you said. :-[ I can see the benefit of waiting til? Spring? so I wouldn't expect new growth as such to be happening, but surely, with careful division and re-potting/husbanding now, all the roots will have the space to settle ready for regrowth?
Be interested to read more informed opinions, tho....