What hardiness zones is Spiraea thunbergii suitable for?

Spiraea thunbergii is suitable for USDA hardiness zones 4, 5, 6, 7, 8.

What are the sun requirements for Spiraea thunbergii?

Spiraea thunbergii requires Full Sun.

How much water does Spiraea thunbergii need?

Spiraea thunbergii has Low water needs.

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Deciduous Shrubs

Spiraea thunbergii

Thunberg spirea

RosaceaeJapan and China

At a Glance

TypeShrub

HabitSpreading

FoliageDeciduous

Height3-5 feet (0.9-1.5 m)

Width3-5 feet (0.9-1.5 m)

Maturity4 years

Growing Zones

USDA Hardiness Zones

4 - 8

Zone 4

Zone 5

Zone 6

Zone 7

Zone 8

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

Frost Tolerancehardy

Key Features

Attracts Pollinators

Deer Resistant

Drought Tolerant

Container Friendly

Maintenancelow

Overview

Spiraea thunbergii is a deciduous shrub reaching 3-5 feet (0.9-1.5 m) tall with a spread of 3-5 feet (0.9-1.5 m), developing a graceful, arching, fountaining form with an exceptionally fine, wispy texture. Leaves are alternate, simple, linear-lanceolate, 0.75-1.5 inches (2-4 cm) long and only 0.1-0.2 inch (3-5 mm) wide — among the narrowest of any Spiraea, creating a willow-like texture unique in the genus. Foliage is bright yellow-green, turning attractive orange-gold to reddish in fall. Flowers are small, white, 5-petaled, 0.3 inch (8 mm) across, borne in clusters of 2-5 along the previous year's slender branches in March to April — one of the earliest-blooming shrubs in the Pacific Northwest landscape. In full bloom, the white flowers smother the arching branches before leaves fully emerge, creating an ethereal, cloud-like effect. Blooms on old wood. Growth rate is moderate at 6-12 inches (15-30 cm) per year. The extremely early bloom can be damaged by late frosts. Not classified as invasive (unlike S. japonica). The cultivar 'Ogon' (Mellow Yellow™) has golden-yellow foliage. A Great Plant Picks recommendation for the Pacific Northwest.

Native Range

Native to Japan and China, occurring on rocky slopes, forest margins, and stream banks. Introduced to Western horticulture in the early 19th century. Named for the Swedish botanist Carl Peter Thunberg.

Suggested Uses

Planted as a specimen, in mixed borders, or in informal hedging where the very early white bloom and fine willow-like texture can be appreciated, spaced 3-4 feet (0.9-1.2 m) apart. Exceptionally valuable for its very early bloom, providing flowers weeks before most other shrubs. The fine texture provides excellent contrast with coarser-leaved plants. Fall color adds late-season interest. Cut branches can be forced indoors in late winter. 'Ogon' (Mellow Yellow™) provides golden foliage year-round. A Great Plant Picks recommendation.

How to Identify

Identified by extremely narrow, willow-like leaves (the narrowest of the common spireas), graceful arching habit, and very early white flowers smothering bare branches in March to April — weeks before other spireas bloom. Distinguished from S. nipponica 'Snowmound' by narrower leaves and earlier bloom time (March vs May). Distinguished from S. japonica cultivars by white (not pink) flowers, earlier bloom, and arching (not mounding) habit. The willow-like leaf shape is distinctive among spireas.

Appearance

Size & Dimensions

Height3' - 5'

Width/Spread3' - 5'

Reaches mature size in approximately 4 years

Colors

Flower Colors

white

Foliage Colors

green

Fall Foliage Colors

orange

gold

red

Bloom Information

Bloom Period

~3 weeks

Spring

White flowers in small clusters along arching branches appear in March to April, lasting 2-3 weeks. This is one of the earliest-blooming deciduous shrubs in the Pacific Northwest, often flowering before forsythia. Blooms on the previous year's wood (old wood). Flowers open before or with emerging leaves. The early bloom can be damaged by late frosts; site in a sheltered location to extend the display.

Detailed Descriptions

Flower Description

White

Foliage Description

Bright yellow-green, willow-like

Growing Conditions

Sun Requirements

Full Sun

Partial Shade

Requires 4-12 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 Range5.0 - 7.5(Neutral)

357912

Soil Types

loamclaysand

Drainage

well drained

Water & Climate

Water Needs

Low

Frost Tolerance

hardy

Time to Maturity

2-3 years

Drought Tolerance

Drought tolerant when established

Care & Maintenance

Care Guide

Water regularly during the first growing season. Established plants are moderately drought-tolerant. Plant in full sun for the most compact growth and heaviest flowering; part shade is tolerated. Tolerates a wide range of soils. Site in a sheltered location to protect the very early flowers from late frost damage. Essentially pest- and disease-free. Does not have the invasive tendencies of S. japonica.

Pruning

Prune immediately after flowering in April to May — this is critical because the plant blooms on old wood. Pruning in late winter removes flower buds. Thin oldest canes at the base. Shorten flowered shoots to strong lateral buds. Maintain the naturally arching, fountaining form; do not shear into a formal shape, which destroys the graceful character. The fine, arching branches are the primary ornamental feature year-round.

Pruning Schedule

late spring

Maintenance Level

low

Container Growing

✓ Suitable for container growing

Minimum container size: 7 gallons

⚠️ Toxicity Warning

Non-toxic