Black Cohosh is a Flowering Woodland Perennial
Black Cohosh — Actaea racemosa — is a woodland plant featuring tall white spires that bloom in midsummer when other forest understory plants have stopped flowering. Black Cohosh flourish in lightly shaded woodland environments with rich soils. Native to deciduous forests in the eastern part of the United States, Black Cohosh is used by home gardeners to add height to the backs of casual perennial borders and in naturalized woodland gardens. Some homeowners also include them in native plant displays and in-home herb patches. Their fuzzy, bottlebrush flowers are a welcome sight in midsummer when spring bloomers are finished for the year and autumn's floral and foliage displays have yet to begin. As a native plant, Black Cohosh is a low-maintenance option that reliably returns year after year. Mature plants may reach up to eight feet tall.
Black Cohosh Thrives in Light Shade and Soils High in Organic Matter
Black Cohosh can be massed together for dramatic effect or interspersed among other understory plants to create an ethereal, fairylike ambiance. The tiny, starlike flowers that make up their trademark spires only come in white, adding to the mystical appearance. Flowering begins at the bottom of the two-foot tall racemes and works to the top. Although this plant does best in slightly shaded areas, it may become stunted and fail to bloom if planted in deep shade — open woodlands are best. Black Cohosh also makes an excellent transitional plant for the outer edges of yards backed by woodlands. Although Black Cohosh does well in moist, well-drained conditions, it also tolerates mild drought. With a spread of between two and four feet, it's essential to provide Black Cohosh with plenty of room to grow. Its horizontal rhizomes can also be dug up in autumn after the bloom season is over and divided to create more plants. This propagation technique results in more uniform plants for those who would like to see them in perennial borders. Still, those who desire to create a natural effect in a woodland garden can achieve that by scattering seeds. This plant provides a habitat for several native butterflies, including Appalachian Azure butterflies.
Besides division, gardeners can also propagate Black Cohosh from seed. Seeds can be started in a cold frame in late winter or early spring to give them a good head start on their first season. Seeds can also be broadcast in autumn when they are to grow and will begin to sprout the following spring. Like most perennials, Black Cohosh won't bloom until its second year, but its dark green, deeply lobed foliage provides an attractive accent in its own right. Black Cohosh also bears attractive fruit and seedpods that provide winter interest in the garden and will self-propagate if some seed is left on the stalk.