What hardiness zones is Corydalis scouleri suitable for?

Corydalis scouleri is suitable for USDA hardiness zones 5, 6, 7, 8, 9.

What are the sun requirements for Corydalis scouleri?

Corydalis scouleri requires Part Shade.

How much water does Corydalis scouleri need?

Corydalis scouleri has High water needs.

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Perennials

Corydalis scouleri

Scouler's fumewort

PapaveraceaeNorth America

At a Glance

TypePerennial

HabitUpright

FoliageDeciduous

Height24–48 inches (60–120 cm)

Width18–36 inches (45–90 cm)

Maturity2 years

Growing Zones

USDA Hardiness Zones

5 - 9

Zone 5

Zone 6

Zone 7

Zone 8

Zone 9

These zones indicate the coldest temperatures this plant can typically survive.

Frost Tolerancehardy

Key Features

Attracts Pollinators

Deer Resistant

Native to North America

Maintenancelow

Overview

Corydalis scouleri, commonly called Scouler's fumewort, is a tall rhizomatous perennial native to moist, shaded forest sites in the Pacific Northwest, ranging from British Columbia south to northern Oregon. Plants grow 24–48 inches (60–120 cm) tall on hollow erect stems bearing three to four large, three- to four-times pinnately compound leaves concentrated near or above the middle of the stem, giving a lush, fern-like appearance. In late spring and early summer, terminal and axillary racemes carry 15–35 rose-pink flowers with purple-tipped outer petals and spurs 0.5–0.8 inches (12–20 mm) long. The species inhabits streambanks, seeps, and moist forest understories from coastal lowlands to foothills, often forming large colonies in disturbed riparian areas. Corydalis scouleri is the largest native Corydalis in the region and is closely related to Corydalis caseana, distinguished by smaller racemes and pink rather than white petals. The plant dies back completely to underground rhizomes in late summer. Mild toxicity has been reported for Corydalis species and handling with care is advisable.

Native Range

Native to the Pacific Northwest of North America, ranging from southern British Columbia south through Washington to northern Oregon. The species grows in moist, shaded habitats including streambanks, seeps, and wet forest margins at low to mid elevations from the coast to the western slopes of the Cascades. It is a characteristic plant of the Pacific coastal temperate rainforest zone.

Suggested Uses

Scouler's fumewort is an excellent choice for large-scale naturalistic planting in moist woodland gardens, rain garden margins, streambank restoration, and shaded bog settings. Its bold, fern-like foliage provides strong textural contrast from spring through early summer, and the pink-purple flower racemes are attractive to bumblebees and other long-tongued pollinators. Best used in settings where summer dormancy is accommodated by surrounding persistent foliage plants.

How to Identify

Scouler's fumewort is identified by its tall hollow stems, 24–48 inches (60–120 cm), bearing three to four large three- to four-times pinnately compound leaves with lanceolate to oblong-elliptic leaflets, 0.8–3 inches (2–8 cm) long, concentrated in the upper half of the stem. Racemes of 15–35 rose-pink flowers with spurred upper petals and purple-tipped outer petals, borne on stems well above the foliage, are diagnostic. The combination of great height, fern-like compound foliage, and pink spurred flowers in wet forest understories distinguishes it from other regional Corydalis species.

Appearance

Size & Dimensions

Height2' - 4'

Width/Spread1'6" - 3'

Reaches mature size in approximately 2 years

Colors

Flower Colors

pink

purple

Foliage Colors

green

blue green

Fall Foliage Colors

yellow

Bloom Information

Bloom Period

~4 weeks

Spring

Scouler's fumewort blooms in late spring to early summer, typically May through June in lowland Pacific Northwest sites. Flowers open progressively from the base of each raceme upward over two to three weeks. Plants at higher elevations or in cooler inland sites may bloom two to three weeks later than coastal lowland populations. The plant goes summer-dormant by July or August, with foliage yellowing and collapsing as temperatures rise.

Detailed Descriptions

Flower Description

Rose-pink with purple tips

Foliage Description

Blue-green to medium green

Growing Conditions

Sun Requirements

Partial Shade

Full Shade

Tolerates up to 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

loampeatsilt

Drainage

moist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

2–3 years

Care & Maintenance

Care Guide

Scouler's fumewort is best suited to naturalized woodland or rain garden settings that replicate its native streamside habitat. Plant rhizomes in autumn in consistently moist to wet, humus-rich soil in full to partial shade; the species does not tolerate dry conditions and will decline rapidly without adequate moisture. Situate plants near water features, rain gardens, or shaded bog margins. No fertilization is required in organically rich soils; top-dress annually with leaf mould or compost. The plant is summer-dormant — mark planting locations to avoid disturbing rhizomes when foliage disappears in July or August. Division is best performed in early autumn when new growth is just beginning.

Pruning

No pruning is needed during the growing season. Allow foliage to yellow and collapse naturally in summer as the plant enters dormancy; do not cut back prematurely, as leaves continue to feed the rhizome through senescence. Remove spent flower stems after bloom if desired for appearance. In autumn, clear away dead foliage and top-dress with compost or leaf litter to mimic the natural forest floor.

Pruning Schedule

summer

Maintenance Level

low

⚠️ Toxicity Warning

Unknown