It is true that the cimicifuga foliage is only about 18 inches high (in general and in my garden). So that might get obscured behind something that is 2-3 feet high. The foliage can be fairly wide when they send up multiple "leaves", so space them a good distance apart (3 to 4 feet).

I don't have any experience with arunca.

My Aruncus dioicus have foliage about 4' tall in dappled shade. The flowers are another foot at least. Wonderful plant for zone 7, and their hardiness rating goes down to zone 3 so you should be fine. Mine get bigger and better every year.

My cimicifuga is planted in deep shade on the north side of the house. It gets about four feet tall and the spiky flower about two more feet. Unless I stake them, most of them flop quite a bit. My Aruncus doicus is fuller, but only about 4 feet tall. I have to stake it too, or it falls over into the path. For me, the cimicifuga is taller and thinner; the Aruncus quite a bit fuller (2-3 feet wide) and not as tall.

Bummer! I didnt know they were floppy. But thanks for the info, that tells me where to put them....

My aruncus in full shade (north side, peaked roof, trees) are a bit floppy, but in dappled shade (trees) they are not floppy at all.

Have you considered thalictrum for your background plant?

If aruncus gets part sun it stays full, more like a shrub, and not floppy at all. Mine is about 4' tall, too, and about as wide.

Jeanne

Here is a picture of Cimicifuga 'Brunette' taken last summer. When in bloom, the plant is easily 6' tall with about 4' of foliage. It gets some afternoon sun. I haven't planted tall plants in front but you could get away with 2', maybe 3' depending on how much of the Cimicifuga foliage you want to see.

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Although these can be a bit slow to establish, once they get going, they make quite the archetectural statement.

Sue

I have both Cimicifuga Hillside Black Beauty and Aruncus growing in morning sun and have never needed to stake them. The Cimicifuga does take a while to reach a substantial height but is now about 4' after about 3-4 years.

Kathie

Kathie, I just got 2 Black Beauties the other day--they really are beauties! One will be in its own spot-- path kinda goes around it. As it turns out the 2nd one wont work where I thought it would. Maybe put them together to create one big plant? They are supposed to "colonize," or spread by rhizomes so I'd be giving them a head start? Make sense?

What do they smell like? The tag says "fragrant," but one of the horticulture websites says "unpleasant odor!"

I see that some plant cimicifuga in deep shade. Does the black beauty retain the color in deep shade also?

Maria

"What do they smell like? The tag says "fragrant," but one of the horticulture websites says "unpleasant odor!"

I have smelled the leaves and they don't smell good but you do have to get close to them.

Maria