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Species Native to Missouri
Common Name: black cohosh
Type: Herbaceous perennial
Family: Ranunculaceae
Zone: 3 to 8
Native Range: North America
Garden Location: Martha Love Symington Missouri Native Shade Garden
Height: 4 to 6 feet
Spread: 2 to 4 feet
Bloom Time: June to July
Bloom Color: White
Bloom Description: White
Sun: Part shade to full shade
Water: Medium
Maintenance: Low
Flowers: Showy Flowers, Fragrant Flowers
Tolerates: Rabbits
Uses: Will Naturalize
Culture
Easily grown in average, medium moisture soils in part shade to full shade. Prefers humusy, organically rich, moisture-retentive soils. Foliage tends to scorch and otherwise depreciate if soils are allowed to dry out. Best sited in locations sheltered from strong winds. This is a slow-to-establish plant.
Noteworthy Characteristics
Black cohosh is an upright, Missouri native perennial which occurs in rocky woods in the Ozark region of the State. It typically grows to a total height (foliage plus flowering spikes) of 4-6’, but under optimum conditions can reach 8’. Small, numerous, creamy white, fragrant flowers appear in late summer to early fall in long, terminal racemes resembling fluffy spires (typically 1-2’ long) rising well above the foliage on wiry stems. Astilbe-like, deeply cut, tripinnate foliage is an attractive deep green. Synonymous with and formerly known as Cimicifuga racemosa. All plants in the genus Cimicifuga have recently been transferred to the genus Actaea. The common name of bugbane is in reference to the odoriferous insect repellant properties of this plant. Cohosh comes from an Algonquin word meaning rough in reference to the appearance of plant rhizomes.
Problems
No serious insect or disease problems. Rust and leaf spot are occasional problems. Foliage generally does not need staking, but taller flower spires may need some support. Flower spires tend to bend toward bright light, particularly when plants are grown in substantial shade. Leaf margins may brown up (scorch) and growth may slow down if soils are not kept consistently moist.
Garden Uses
Adds architectural height and late summer bloom to a shaded part of the border or shade garden. Also effective in woodland gardens, cottage gardens and naturalized areas. Best in groups, although single plants have good specimen value once established. White flower spires are generally more demonstrative in front of darker backgrounds. Deep green foliage provides excellent texture and color to the landscape throughout the growing season.