Blue Cohosh
Caulophyllum thalictroides
Common Names
Blue Cohosh, Blue Ginseng, Papoose Root, Squaw Root, Garden Blueberry, Umbrella Leaf
Summary
Blue cohosh, Caulophyllum thalictroides, is a rhizomatous perennial native to eastern North America. It forms clumps in shade and grows about 0.5–1 m tall with blue-green, lacy foliage and leaves divided into three leaflets; spring flowers are greenish-yellow, followed by deep blue, berry-like seeds that appear in late summer. Cultivation favors moist, humus-rich acidic soil in deep or partial shade, tolerating clay or loam, and USDA zones 3a through 8b; propagation is by seed or division of root crowns or rhizomes in autumn, with seeds requiring outer coat removal and a long germination cycle of 500–900 days, after which plants may be grown in flats for about two years to develop a root-rhizome. Historically used as a gynecologic remedy and general tonic, with safety concerns and toxicity warranting caution, and pregnancy contraindicated.
Lifecycle
Annual, Biennial, Perennial
Height
12-39.5 inches
Spread
4-20 inches
Hardiness Zones
Zones 3-8
Sunlight Requirements
Ideally partial shade to full shade.
Soil Type
Moist, loamy soil rich in organic matter, slightly acidic (pH 5–6).
Soil Drainage
Moist but well-drained soil.
Soil pH
5-6
Bloom Color
Insignificant
Bloom Time
Spring
Foliage Color
Green
Fall Foliage Color
Green
Leaf Lifecycle
Deciduous
Growth Rate
Slow to very slowly; 2–5 years to reach ultimate height.
Seasons of Interest
Spring, Summer, and Fall.
Propagation Methods
Seeds, Division of root crowns or rhizomes (autumn), slow vegetative spread via rhizomes
Attracts Wildlife
Attracts bees, Attracts birds