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