They do grow like weeds for me in zone 4a. Too much like weeds, in fact. pH ~7.0, heavy clay base. I am thinking since Michael Dirr wasn't impressed with them (a more southerly gentleman), maybe they don't do too well where winters (or summers) are too warm. They come from Siberia.

My plants are mulched, but that is the only attention they get.

Thanks, I read that they like lots of water, and where they are is sort of dry. I'll try to water them more. I'll check the ph too. We usually get cold winters, so hopefully it's just the water or ph level. I have some currants in the vicinity and they aren't doing anything either.