What hardiness zones is Corydalis scouleri suitable for?

Corydalis scouleri is Scouler's fumewort (Scouler's corydalis), an upright deciduous perennial growing 24-48 inches (60-120 cm) tall and 18-36 inches (45-90 cm) wide — one of the largest Corydalis species. Rose-pink tubular flowers with purple tips and a spur 0.5 inch (1.3 cm) in dense terminal racemes 4-8 inches (10-20 cm) in May-June (4 weeks). Blue-green to medium green finely dissected bipinnately compound fern-like leaves 6-12 inches (15-30 cm). In Papaveraceae. Named for John Scouler, who collected in the Pacific Northwest in the 1820s. Native to the Pacific Northwest — British Columbia through Oregon in moist coniferous forests and stream banks. Goes summer-dormant in hot dry conditions — the above-ground growth dies back by August. This summer dormancy in dry climates is the primary limitation. In the maritime Pacific Northwest with cool moist summers, the foliage persists longer. Spreads by fleshy rhizomes to form colonies. Requires consistently moist to wet soil — not drought-tolerant. Deer-resistant. Toxicity unknown (related to alkaloid-containing genera in Papaveraceae). Zones 5-9. Part shade to full shade. Growth rate is moderate to fast.

Native Range

Native to the Pacific Northwest of North America — from British Columbia south through Washington and Oregon. Found in moist coniferous forests, stream banks, and wet ravines.

Suggested Uses

Grown in moist woodland gardens, stream banks, rain gardens, and native plant gardens in the Pacific Northwest, spaced 18-36 inches (45-90 cm). Large fern-like foliage. Summer-dormant in dry conditions. Native to PNW. Deer-resistant. Zones 5-9.

How to Identify

Identified by rose-pink spurred tubular flowers in dense terminal racemes above blue-green finely dissected fern-like foliage on a large upright perennial 24-48 inches (60-120 cm). The large size (up to 4 feet / 1.2 m) distinguishes C. scouleri from most other Corydalis species (under 18 inches / 45 cm). In Papaveraceae.

Appearance

Size & Dimensions

Height2' - 4'

Width/Spread1'6" - 3'

Reaches mature size in approximately 2 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~4 weeks

Spring

Late spring to early summer (May-June). Rose-pink tubular flowers with purple tips and spurs in dense terminal racemes 4-8 inches (10-20 cm). 4 weeks. Bee-visited. Summer-dormant in dry conditions.

Detailed Descriptions

Flower Description

Rose-pink with purple tips, tubular with a spur 0.5 inch (1.3 cm) long, in dense terminal racemes 4-8 inches (10-20 cm)

Foliage Description

Blue-green to medium green, finely dissected (fern-like), bipinnately compound, 6-12 inches (15-30 cm); the fine dissected texture creates an airy fern-like mound

Growing Conditions

Sun Requirements

Partial Shade Full Shade

Requires 1-4 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 7.0(Neutral)

357912

Soil Types

loam peat silt

Drainagemoist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

2-3 years

Care & Maintenance

Care Guide

Part shade to full shade (1-4 hours). Consistently moist to wet soil pH 5.5-7.0. Not drought-tolerant. Goes summer-dormant in dry conditions. Plant among ferns or other shade perennials that fill the gap after dormancy. Spreads by rhizomes. Cut dead summer-dormant foliage. Deer-resistant. Toxicity unknown. Zones 5-9.

Pruning

Cut dead summer-dormant foliage to the ground in late summer (August-September). No other pruning needed. Thin rhizome spread if the colony exceeds desired area.

Pruning Schedule

summer

Maintenance Level

low

⚠️ Toxicity Warning

Unknown