Black Cohosh
(Actea racemosa L.)

botanical information

Black cohosh, Actea racemosa L., formerly Cimicifuga racemosa (L.) Nutt, is a member of the Ranunculaceae family and is a native medicinal plant found in rich woodlands from Maine to Georgia, west to Missouri, Indiana, and Ontario.  In North Carolina it can be found at elevations up to 4,000 feet.  It is an herbaceous perennial reaching a mature height well above four feet and can grow at a rate of eighteen to twenty-two inches per month during the growing season.  The leaves are large with three pinnately compound divisions and irregularly toothed leaflets.  Tall plumes of cream to white flowers, on a wand-like raceme, bloom from May to July, often-towering over six feet.  From August to October, seeds develop in capsules and make a rattling sound when they are mature and ready to be harvested. 

medicinal uses

Native Americans used black cohosh for a variety of medical conditions ranging from gynecological problems to snake bites.  Physicians made use of it in the 19th century to treat fever, menstrual cramps, and arthritis.  In Europe, black cohosh has been used for over 40 years as a treatment for menstrual pain.  In recent years, this material has been used as a treatment alternative to mainstream hormone replacement therapy (HRT) and for premenstrual syndrome (PMS).  Other traditional medicinal uses include rheumatism, sore throats, and bronchitis.

selecting a planting site

Black cohosh prefers a rich moist soil that is well drained with high organic matter.  In its natural habitat, it is usually found in shaded or partially shaded areas.  Black cohosh does well in a woods cultivated or artificial shade environment.  

If an open field is used for production, shade structures should be erected.  Typically, a wood lath structure or polypropylene shade structure is used.  For forest culture, select a site with good air and water drainage in an area shaded by tall, preferably hardwood trees.  Look for an area where other woodland plants grow such as mayapple, trillium, bloodroot, ginseng, or perhaps a native stand of black cohosh.

 Black cohosh has been known to tolerate more light and soil variations than other woodland botanicals provided there is adequate moisture available.  If black cohosh is not grown in ideal forest soils, raised beds are highly recommended, especially for moist or clay soils.  Make sure sufficient compost or other organic material is added.  Soils with a pH range of 5 to 6 are ideal for growing black cohosh.

planting

Propagation is typically done through seed or root division.  Black cohosh is more easily propagated by dividing the rhizomes in spring or in fall.  Plants can be started indoors from seed or seed can be directly sown into the ground, but the rhizome divisions allow for a faster harvestable plant, and, large quantities of seed are not readily available commercially.    

To plant rhizomes, cut the roots into vertical sections, two to three inches in length, making sure there is at least one bud attached.  There can be up to fifteen buds on a rhizome of one black cohosh plant.  Any fibrous roots connected to the rhizome pieces can remain attached.  In a well-prepared three-foot wide bed, plant rhizome pieces deep enough to cover the top of the rhizome with two inches of soil (usually four to six inches deep).  Stagger plantings eighteen to twenty-four inches apart, making sure the bud is pointed upright when placing the rhizome pieces in the ground.  Mulch beds with at least three inches of shredded hardwood mulch or leaf mulch.  Add mulch as needed throughout the growing seasons.  Plants should be ready to harvest three to five years after planting.

 In the fall, the mature seed can be harvested, and then sown in the ground immediately.  Collect the seed just as the pod starts to split open.  With seedbeds prepared, plant the fresh seeds one and one-half to two inches apart, approximately one-quarter inch deep.  Cover with a two-inch layer of mulch and keep moist.  Germination should occur the following spring but most seeds may not emerge until the second spring.  Keep young seedlings moist and shaded.  Transplant into regular planting beds when a second set of true leaves emerge.  Harvesting of the root, usually, can begin four to six years after seeding.  Researchers are currently conducting seed germination studies for black cohosh, and as new information becomes available, this publication will be updated.  

insects and diseases

Common diseases found on black cohosh consist of leaf spots, including Alternaria, and root rots, including Rhizoctonia.  Rhizoctonia solani caused damping off in young emerging seedlings of black cohosh in a 2003 study done by R. D. Reeleder, Canadian Journal of Plant Pathology.  Two other leaf spots mentioned in Index of Plant Diseases in the United States are Ascochtya actaeae and Ectostroma applatum.    

Common insects that attack black cohosh include cutworms and blister beetles.  Other critters that forage on black cohosh include deer, opossum, rabbits, slugs, and snails.  On a positive note, butterflies and hummingbirds are quite attracted to the flowers.

harvesting, cleaning, and drying

Most black cohosh is harvested in the fall, primarily because plants are at their peak in weight and bioactive constituents.  There are some buyers who will purchase it in the spring as well.  Already mentioned, the rhizome is the part harvested.  Since it has a dark, thick and knotty nature, digging is easiest with a spading fork.   

 Shake the roots free of dirt and carefully remove only roots that are black cohosh.  It is not acceptable to include foreign particles.  Protect from the sun and heat; do not allow the roots to dry out.  Since fresh roots are susceptible to mold, do not wash roots until ready to process.  Mixing the roots with sphagnum moss and storing in mesh bags, burlap bags, or boxes in the cooler will help to reduce mold forming.  Check often to prevent roots from drying out and stir the roots to avoid additional mold growing and to allow some aeration.  When ready for processing, it is recommended to wash black cohosh roots with a pressure hose.  The knotty roots can be quite a challenge to clean.  Take great care in protecting the roots from damage as they are cleaned.  Remove all particles of dirt.  

markets  

Black cohosh was identified as one of the fastest growing herbal products in 1998.  Just a few decades ago, the vast majority of black cohosh that was harvested was sent to Europe for processing and consumption.  In the past ten years, interest in North America for this botanical has increased dramatically.  Current supplies come mostly from the harvesting of native populations.  Only a small quantity of cultivated material has made its way to market.  Naturally occurring populations will not satisfy the expected increase in demand.  Cultivation is to be encouraged.  This would allow native populations to regenerate and multiply. 

 For the nursery trade, black cohosh is gaining popularity among shade gardeners, nursery container growers, and landscapers.  Selections of native species are available as well as varieties with purplish leaves and stems.  As a background plant in a shade garden, the gracefulness of this plant, in flower, will hardly go unnoticed.

Cech, Richo. 2002. Growing At-Risk Medicinal Herbs. Horizon Herbs. Williams, Oregon. 314 pp. 

Greenfield, Jackie, and Jeanine M. Davis. 2004. Medicinal herb production guides. North Carolina State University, Raleigh, NC. 

Greenfield, Jackie, and Jeanine M. Davis. 2003. Collection to commerce: western North Carolina non-timber forest products and their markets. North Carolina State University, Raleigh, NC. 106 pp. 

 Persons, W. Scott, and Jeanine M. Davis. 2004. Green Gold: A Grower’s Guide to the Profitable Production of Ginseng, Goldenseal, Ramps, Black Cohosh, Bloodroot, and Other Woodland Medicinal Plants. Bright Mountain Books. Asheville, NC. To be published.

 Radford, Albert E., Harry E. Ahles, and C. Ritchie Bell. 1968. Manual of the Vascular Flora of the Carolinas. University of North Carolina Press, Chapel Hill, NC. 1183 pp.

 Reeleder, R.D. 2003. The ginseng root pathogens Cylindrocarpon destructans and Phytophthora cactorum are not pathogenic to the medicinal herbs Hydrastis canadensis and Actaea racemosa. Canadian Journal of Plant Pathology. Vol 25, Number 2, pp 218-221.    

Strategic Reports. 2002. Analysis of the economic viability of cultivating selected botanicals in North Carolina. A report commissioned for the North Carolina Consortium on Natural Medicinal Products by North Carolina State University, Raleigh, NC. 244 pp.

 Sturdivant, Lee, and Tim Blakley. 1999. Medicinal Herbs in the Garden, Field, and Marketplace. San Juan Naturals. Friday Harbor, Washington. 323 pp.

 US Department of Agriculture, Crops Research Division Agricultural Research Service. 1960. Index of Plant Diseases in the United States, Agriculture Handbook No. 165. Washington, DC. 531pp.

The North Carolina Arboretum is grateful to Jackie Greenfield and Jeanine M. Davis for their contributions to this publication, including excerpts from their publication “Medicinal Herb Production Guides." The Arboretum also wishes to thank Richard Rice for his artistic renditions of the herbs. The Superb Herbs Web site and the documents provided were made possible by a grant from the NC Department of Agriculture and Consumer Services, found on the Web at www.ncagr.com.