Black cohosh is an herbaceous perennial native to North America. It can grow up to 6 feet tall and forms flower stalks that can be 20 inches high. The huge, serrated leaves can grow to 39 inches. Black cohosh flowers are white and produce a sweet smell that repels some pests, hence, its common name, “black bugbane.” Black cohosh blooms during summer and can thrive in one location for many years. It is easy to grow and requires little effort to maintain in most temperate regions.
Plant black cohosh seeds in indoor containers during the fall to allow them to germinate by spring. Water once a week and keep them in a warm, dry location that receives full sunlight.
Choose an outdoor planting location that receives some morning sunlight but complete shade in the afternoon.
Spread 2 to 3 inches of well-rotted manure over the planting site, and use a garden tiller to mix it with the soil.
Transplant the black cohosh seedlings in the spring after they have sprouted. Dig a hole slightly bigger than the root ball, insert the plant and cover with soil. Water lightly to compact the soil around the roots.
Water black cohosh three times per week after transplanting, enough to keep the soil moist at all times. Never allow the soil to dry out, or the plant will wilt. Reduce watering to once per week during winter, and then resume the initial schedule in the spring.
Feed black cohosh with a dressing of aged organic compost each spring. Spread the compost out around the stem, without allowing it to directly touch any portion of the plant. Start the layer of compost 2 to 3 inches away from the stem.
Remove dead or fading flowers to prevent the plant from wasting nutrients forming seeds. Removing the dead flowers will also encourage more flowering during the initial season. At the end of the blooming season, leave some dead flowers so the seed pods forms. The pods are ornamental during fall and winter.