If you’re looking for something a little different for a shady border or to keep your azaleas company, have you considered black cohosh, also known as bugbane, baneberry, black snakeroot, or my favorite, fairy candles? For consistency I’ll call it cohosh here.
Perhaps you recognize the name ‘black cohosh’ from traditional folk medicine. One of 18 species worldwide, our native North American cohosh was once used to treat everything from snake bite to lung ailments to chirldbirth and menopause. It is still available today as an herbal supplement.
No matter what you call it, all varieties make good garden plants, especially the darker-leaved cultivars. The variety I grow, Pink Spike, is terrific. There are several others just as nice. If you’ve got a bit of moist loam in dappled or part shade, you might like to try growing this unusual beauty with its fascinating history.
The great thing about cohosh (or actaea, previously classified as cimicifuga and still sold under that name) is the visual interest it brings even out of bloom. I consider it a foliage plant first and foremost, with the flowers as a bonus. Bottlebrush-like blooms eventually rise well above the foliage, and on a mature clump the display can be absolutely captivating. But the foliage looks great all season. It is also a breeze to care for. (See the profile chart at the end of this post.)
A few newer cultivars are strongly fragrant too, while the native form is mildly pungent. All range between 3 feet and 7 feet tall in bloom, depending on the cultivar. The hybrids are all on the short end of this range, so they are easily incorporated into most settings.
To be clear, I recommend growing cohosh for its ornamental and olfactory value only, not for medicinal use. Ingestion can have significant side effects, some species are highly poisonous, and potency is impossible to control in a home garden. So please, just grow it for fun. If you want to consume it as a supplement, buy it in supplement form.
First, the Natives
Actaea racemosa is our tallest native species, eventually reaching 7 feet in bloom. It blooms (white or cream) in midsummer. The spring blue azure butterfly uses this plant as a larval food source.
White Baneberry (Actaea pachypoda) blooms early and forms highly poisonous white berries dotted with a purple spot held on bright red stems all summer, hence the common name Doll’s Eyes.
Both of these species have unremarkable green foliage and do best in semi-wild woodlands where children and pets aren’t likely to accidentally eat them. Unless you have just such a spot, they aren’t the best choice for suburban gardens. But ornamentally, they’re interesting plants just the same.
Fortunately the commercial cultivars are more versatile and easier to work with, so let’s talk about a few.
Cultivars to Consider
One of the best things about the cultivated varieties of cohosh is their dark-toned, deeply cut foliage. (There are confusing latin spellings in this group so I’ll stick with cultivar names.) Unlike natives, most nursery-bred cohosh cultivars open late, usually in September, and stay in flower for at least a month. The substantial blooms are also fatter and more dense than the native varieties.
(photos from the web)
Hillside Beauty and Brunette have bronze to purple-black basal leaves with bushy wands of pale pink-white flowers in fall. Chocaholic is bronzy-green with soft mauve-white flowers. The foliage gets about 3 feet tall and wide, with flowers stalks reaching 4 feet. Any of these will add contrast and structure without overwhelming their neighbors.
Black Negligee and Pink Spike are somewhat shorter at 3 to 3 1/2 feet and feature burgundy to olive-bronze leaves, pale pink to white florets and a pleasing fragrance. Fat wine-colored buds open from the bottom up, providing a two-toned effect. The wands last a long time.
I grow Pink Spike and find its pronounced scent unique and refreshing. To my nose, it smells like grape lollipop infused with wintergreen, or maybe sarsparilla….or cotton candy? On a sunny day the bewitching scent wafts across the garden. You’ll just have to grow it and sniff for yourself! Black Negligee is supposedly quite fragrant too, as are all of the Actaea simplex cultivars.
The foliage of Pink Spike starts out burgundy-black, turning dark olive by midsummer. The richest coloring is achieved in mostly shade. Even when it has turned olive, it still adds definition and depth to shady spots.
Companion Plants
Cohosh fits easily into landscape because it looks good with everything. If you like charteuse or yellow, you could play it off Sambuca Lemony Lace (an elderberry with lacy golden foliage), Japanese hakone grass All Gold, or Aralia Sun King for some serious pop.
Try it with anemones, asters, astilbes, emerald goatsbeard or quilted and striped hostas. Silvery companions like ghost ferns, brunnera Jack Frost, lamium or variegated groundcovers all make stunning combinations.
Cohosh would also make a wonderful backdrop for hardy fall mums, perhaps set against a split rail fence or a foundation wall. You don’t have to have woodlands to grow cohosh!
If you have mostly shrubs, pair cohosh with fothergilla, azalea, viburnum, variegated dogwoods, sweetshrub, even hydrangea. Just make sure the flower spikes won’t interfere with any low overhead branches.
As for pollinators, bees visit the flowers occasionally but wasps and flies love it. I haven’t noticed many butterfies, probably because it opens so late here, and most butterflies are gone by then.
Growing Cohosh
Cohosh is a woodland plant, so mostly shade or dappled shade is perfect. (Actual woods aren’t necessary if you amend the soil.) A bit of morning sun is okay but no hot afternoon sun. Get potted plants in the ground promptly, or plant bare rhizomes in fall in groups of 3 to 5, about a foot apart. The soil should be neutral to slightly acidic, rich in organic matter and well drained. If you have dense clay, mix in some compost or leaf duff. A good quality mulch is a good idea too, since it will help the soil retain moisture as it slowly decomposes.
It may take a year or two for new plants to reach full size, but you’ll get the benefit of the foliage the first season. Feed initially in spring with a slow-release granular fertilizer designed for acid-loving plants. It may not need it every year. Cohosh spreads very slowly, so it can remain in place indefinitely without over-running things or needing to be divided. Over time it should make an impressive clump.
Unbothered by pests, deer, and rabbits, cohosh is hardy and disease resistant. Its biggest requirement beyond shade is even moisture. Don’t let the roots get bone-dry. (I have mine near our birdbath, which gets rinsed frequently.)
Maintenance is really minimal. Deadhead or cut the entire plant to the ground after a few hard frosts, or leave until late winter.
What’s Not to Like
I hope I’ve convinced you to give “fairy candles” a try. Besides cohosh’s intriguing provenance as a medicinal herb, it brings a lot to the garden in exchange for minimal care. Not only will it add contrast and drama, both the foliage and flowers last well in arrangements, too. (Make sure arrangements are out of reach of any inquisitive kitties!)
A mature clump in full bloom (especially backlit) is a sight both you and your neighbors will marvel at, and it will softly perfume the waning warm days. Let us know in the comments if you grow cohosh, and if so, which cultivars you like.
