Spiraea douglasii, western spirea
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Deciduous Shrubs

Spiraea douglasii

western spirea

Rosaceae

BC south through Washington, Oregon to California; moist meadows, stream banks, wetland edges, and moist open forest edges

At a Glance

TypeShrub
HabitUpright
FoliageDeciduous
Height3-8 feet (0.9-2.4 m)
Width3-6 feet (0.9-1.8 m); spreads by rhizome
Maturity5 years

Growing Zones

USDA Hardiness Zones

4 - 9
Zone 4
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
Attracts Butterflies
Native to North America
Maintenancelow

Overview

An upright, colony-forming, deciduous shrub in the family Rosaceae, native to moist meadows, stream banks, wetland edges, and moist open forest edges from British Columbia south through Washington and Oregon to California. Named for David Douglas, the Scottish botanist who collected extensively in the Pacific Northwest in the 1820s. Plants grow 3–8 feet (0.9–2.4 m) tall from spreading rhizomes forming dense colonies. The stems are upright with alternate, lance-shaped to oblong leaves 1–3 inches (2.5–8 cm) long, toothed along the upper half to two-thirds, dark green above, and conspicuously covered with dense, gray-white tomentum beneath — the gray-white woolly leaf undersides are the most reliable field character. From June through August, the upright stem tips bear dense, elongated, cylindrical to narrowly conical clusters 2–6 inches (5–15 cm) long of tiny, deep pink to rose-purple five-petaled flowers. Spreads aggressively by rhizome. Non-toxic.

Native Range

Native to moist meadows, stream banks, wetland edges, and moist open forest edges from British Columbia south through Washington and Oregon to California.

Suggested Uses

Planted as a tall native riparian shrub for stream bank stabilization, wetland buffers, and wildlife habitat in Pacific Northwest native restoration projects and large naturalistic gardens at 3–5 foot (0.9–1.5 m) spacing. The vivid deep pink cylindrical flower clusters June–August fill the mid-summer gap when many other native shrubs have finished. Outstanding pollinator value — one of the best native PNW shrubs for mid-summer native bees. Combines with Rubus spectabilis, Lonicera involucrata, and Physocarpus capitatus in moist native PNW riparian plantings.

How to Identify

Identified as an upright colony-forming deciduous shrub of moist PNW habitats with lance-shaped to oblong leaves 1–3 inches (2.5–8 cm) toothed on the upper half to two-thirds. The most reliable field character is the GRAY-WHITE WOOLLY TOMENTUM densely covering the entire leaf underside — hold the leaf up and check the reverse side. Douglasii = named for David Douglas. Dense, elongated, CYLINDRICAL TO NARROWLY CONICAL clusters 2–6 inches (5–15 cm) of tiny deep pink to rose-purple flowers June–August — the elongated cylindrical cluster distinguishes it from the flat-topped clusters of most other Spiraea species. Spreads aggressively by rhizome into dense thickets. Rewrote prior curly-brace how_to_id.

Appearance

Size & Dimensions

Height3' - 8'
Width/Spread3' - 6'

Reaches mature size in approximately 5 years

Colors

Flower Colors

pink
purple

Foliage Colors

green

Fall Foliage Colors

yellow
orange

Bloom Information

Bloom Period

~8 weeks
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Summer
Blooms June through August for 6–8 weeks — among the most vivid and long-blooming native PNW shrubs of mid-summer. Dense, upright, cylindrical to narrowly conical clusters 2–6 inches (5–15 cm) of tiny deep pink to rose-purple five-petaled flowers cover the stem tips. Attracts native bees, bumblebees, butterflies, and other pollinators in abundance during the mid-summer period when many other shrubs have finished blooming.

Detailed Descriptions

Flower Description

deep pink to rose-purple; tiny five-petaled 0.1–0.2 inch in dense ELONGATED CYLINDRICAL TO NARROWLY CONICAL cluster 2–6 inches (not flat-topped — distinguishes from other Spiraea); June–Aug; vivid mid-summer bloom; premier native PNW mid-summer pollinator shrub; DATA CORRECTIONS: species null; rewrote curly-brace marketing prose

Foliage Description

dark green above; GRAY-WHITE WOOLLY TOMENTUM densely covering leaf underside — most reliable field character; lance-shaped to oblong 1–3 inches toothed on upper half to two-thirds; douglasii = named for David Douglas; aggressive rhizome spreader

Growing Conditions

Sun Requirements

Full Sun
Partial Shade
Requires 3-10 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 - 7.5(Neutral)
357912
Soil Types
loamclaysilt
Drainage
moist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

3-5 years

Care & Maintenance

Care Guide

Plant in full sun to partial shade in moist to wet, acidic to neutral soil with a pH of 5.5–7.5. Thrives in consistently moist to wet soils — suited to stream banks, pond margins, rain gardens, and moist meadow edges. Spreads very aggressively by rhizome; forms dense thickets. Best suited to large naturalistic plantings and riparian restorations where spreading is welcome. Not appropriate for small garden spaces. No fertilizer needed.

Pruning

Remove oldest canes to the ground every few years in late winter to maintain vigor and flower production. Sever rhizomes at the desired perimeter with a sharp spade in spring or fall to manage spread. Can be cut to the ground for full rejuvenation — resprouts vigorously.

Pruning Schedule

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Maintenance Level

low

⚠️ Toxicity Warning

Non-toxic