Yes, most of the standard varieties should survive the winter in Lower Michigan. Some of the "newer" forms that involve C. rosea ('Sweet Dreams', 'Heaven's Gate', etc.) are likely less hardy, as well as most of the even newer forms such as 'Autumn Blush', 'Red Shift', etc. As mentioned, your issue is likely winter wetness. Has anyone else experienced even good ol' 'Moonbeam' getting tired-looking (less vigorous/profuse) after only 2-3 years? I'm beginning to wonder if most/all the genus is generally short-lived. Certainly the C. grandiflora types are, although they self-sow readily.

OK, I did the deed, divided it and did note a difference in the growth habit of Mardi Gras vs. the ordinary one mentioned in my original post. With the ordinary one, it made no difference how small the divisions were. A single rosette still produced a blooming sized plant by midsummer. However that plant also separated into individual plants much easier when dug. When I dug the Mardi Gras, I actually had to cut the clump into divisions. I ended up with 3 clumps, each with 4-5 rosettes, but I didn't feel comfortable trying to make any smaller divisions. They just didn't separate easily like my other plant. So wieslaw, I agree. Not all Helenium are created equal in my extremely limited experience. Kevin

Anything that needs to be coddled doesn't belong in my flowerbeds so I'll pass on Moonbeam--reluctantly--unless I come across it on a markdown table at some point and try it again with that below grade planting. Sienna Sunset didn't come back either but that was definitely my fault so I'll give that one another chance if I find it somewhere. Zagreb has more than outgrown the spot where I originally planted it so that'll get divided this year and planted in a few other spots around the garden.

I am a relentless deadheader and I think it keeps my plants blooming longer. I also do not prune my Moonbean, I just leave it to overwinter on its own and it comes right back. It also prevents unwanted volunteers from coming up the next year. This year, because of illness in the family, I did not do the daily deadhead on my Lychnis, and it has almost stopped blooming already. Usually, I have blooms until late fall.