Best grown in shady woodland areas in rich, moist, neutral to slightly acidic soils. Needs consistently moist soils that do not dry out. Plants may be grown from seed, but usually will not flower until the third or fourth year. May be divided, but established plants are generally best left undisturbed. Can spread very slowly by rhizomes over time to form colonies.
Blue cohosh is a Missouri native perennial which grows 1-3' tall on strong, upright stems. It is valued not for its flowers but for its lacy, ternately-compound, blue-green foliage and its erect clusters of blue, fruit-like seeds. Foliage is suggestive of meadow rue (Thalictrum), hence the species name. Leaves appear at mid-stem, emerging a smoky blue in spring and turning bluish-green at maturity. Young plants are covered with a whitish, waxy bloom. Inconspicuous, brownish-green to yellowish-green flowers (1/2" diameter), each with 6 pointed sepals, appear in spring. Flowers give way in summer to attractive blue berry-like seeds (outer seed coating turns fleshy and blue as seeds mature) which resemble small grapes and provide good ornamental interest into fall after foliage decline has occurred.
No serious insect or disease problems. Slow to establish from seed. Berry-like seeds are poisonous.
Blue cohosh is best in groups or massed in woodland gardens or shady wild gardens.
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Missouri Botanical Garden
4344 Shaw Blvd., St. Louis, MO 63110(314) 577-5100 hours and admission
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Faust Park, 15193 Olive Blvd. Chesterfield, MO 63017(636) 530-0076 hours and admission
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Hwy. 100 & I-44 Gray Summit, MO 63039(636) 451-3512 hours and admission