I love Astilbes. Had several dozen at one time. Around the pond, next to the deck, in the shade of an apple tree. But over 15 years, some died out naturally, some failed because of additional sun, and some died from being too shaded by brambles.
So this year I decided to get some new ones growing. There are really fancy ones, but I'm satisfyied with "regulars". I found bare-roots on sale at ebay. 25 for $60. I bought a set of 25 and planted them in the backyard where a few remaining Astilbes were growing happily each year.
I think I didn't plant them properly. I went by the included instructions, but they never seemed to set roots. Well, it was in almost pure compost and maybe they don't like that. And it is sunnier in that spot than it used to be (a new deck, new shade patterns). And it has been really dry in June here, so I maybe should have watered them more often.
I lost 1/3 of the backyard bunch. I have shadecloth over them now, and some are doing better.
I also added some to a front yard island in the shade of a Saucer Magnolia tree. I'm fighting deer now, and they ate up all my hostas. But they don't like Astilbes much. They pulled a couple up but didn't eat them. I replanted them. Some are starting to flower. I water them deeply every 3 days.