Answer: I think this may be too much sun for it, especially if it is afternoon sun and/or the soil is not evenly moist. This is a plant for shade to part shade meaning full shade or dappled light or some morning only sun. If it is in noon-time sun or afternoon sun and/or there is enough sun to keep your Russian sage (a full sun plant) and Baptisia (another full sun plant) happy then it is probably way too sunny for the Cimicifuga. Also, unless you have one of the sun tolerant hostas it may also be too bright for that plant. I hope this helps.
Q&A Library Searching Tips