Pretty sure I had this cultivar years and years ago, when first starting out. I experienced the same thing. I thought maybe the wet winters did it in, but it could be that A. filipendula is a short lived species in general. That would be my guess anyway...

Don't think dividing would help at this point. Sorry! ;-(
CMK

This post was edited by christinmk on Fri, Feb 1, 13 at 14:05

Most of my achillea used to die out if they weren't divided into bits and replanted in new soil. What have you got to lose? It won't come back from the grave without some kind of help on your part.

You could try planting it in the lawn, that's one place where it never seems to have any problem thriving..... Ooops, I almost used the weed word.

I think I will dig it up and try to replant it in small pieces in another bed. As you said,Kato, what I have got to lose?

I've had mine for about 10 years, I've divided it twice and so far at least it's never failed me.