I haven't seen any Cimicifuga/Actaea racemosa growing under the black walnuts that grow on the land we live on, but that doesn't necessarily mean the cimicifuga isn't juglone-tolerant.

The University of Missouri College of Agriculture apparently did a study on Cimicifuga/Actaea racemosa growing in proximity to black walnut trees. You could try contacting them and finding out what the results were. See the link below for a description of the study. It's listed under "Experiment 3: Evaluating the suitability of black cohosh as an understory agroforestry intercrop with black walnut" on the page linked below. Their contact info is also on that page in the column on the left.

Of course, someone else that has planted cimicifuga under black walnuts, or seen it growing there may know better than I! Good luck.

Here is a link that might be useful: University of Missouri: Actaea racemosa

I emailed UMC but no response. I do know somebody who works there, maybe he can find out for me. But from previous posts here, I think I will be pretty safe. Thanks.

ignorant of the potential effects, I planted a number of Cimicifuga americana under the drip zone and leaf canopy of a black walnut. I have never removed the leaves or husks from this garden. 4 years later the plants are still growing strong along with goatsbeard, mayapple, solomon's seal, carrion flower, and starflower. I have lost mountain laurel and white pine in the vicinity.

Since I started this thread, I planted a small cimicifuga under my old black walnut, and when it disappeared last July, I just decided it wouldn't work. But it seems that underground, things were happening, because this year it came up huge and beautiful. So I guess there is no problem!