I planted mine in '08. Little Red Gem (I think, just had tenufolia on the tag). It has bloomed on 6-5-09, 6-5-10, 6-24-11. Everything was way late last year. I am moving it this year to a place where it will get more sun.
The leaves are really ferny and fine. It was one of the nice things that the former owner left us. I know it's sort of an alpine plant, but I don't know what else to do with it. When we were digging there last year, I moved on of the two so it would not be damaged, but the other was not moved. Poor thing has not bloomed in a few years.
I moved mine to the herb garden a few years ago where it increased in size and blooms (9 last year) steadily.
This year the Comptonia (Sweet Fern) has grown so large tit has moved into the fern leaf peony space.
As a consequence the fern leaf is smaller and will have only 5 blooms.