Hydrangea macrophylla, bigleaf hydrangea
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Deciduous Shrubs

Hydrangea macrophylla

bigleaf hydrangea

HydrangeaceaeAsia

At a Glance

TypeShrub
HabitMounding
FoliageDeciduous
Height4–6 feet (1.2–1.8 m)
Width4–6 feet (1.2–1.8 m)
Maturity4 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
Attracts Butterflies
Container Friendly
Maintenancemoderate

Overview

Hydrangea macrophylla (Hortensia/Mophead Group), commonly called bigleaf hydrangea or mophead hydrangea, is a large deciduous shrub in the family Hydrangeaceae native to the Pacific coast of Honshu, Japan. It is one of the most widely planted deciduous flowering shrubs in Pacific Northwest gardens, thriving in the region's mild, moist climate. Mophead cultivars produce large, rounded flower heads 6–12 inches (15–30 cm) across composed almost entirely of sterile florets, each with four to five broad, petal-like sepals. Flower color is pH-dependent: in acidic soils (pH below 6.0 — common in Pacific Northwest gardens) flowers are blue to purple; in alkaline soils (pH above 7.0) they are pink to red; at intermediate pH, colors are mixed or mauve. Adding aluminum sulfate acidifies soil and deepens blue tones; adding lime raises pH toward pink. Plants grow 4–6 feet (1.2–1.8 m) tall and wide with an arching, mounding habit. Traditional cultivars bloom on old wood (previous season's stems) — late frosts or improper autumn pruning removes the following year's flower buds; remontant cultivars ('Endless Summer', 'Let's Dance' series, 'Twist-n-Shout') bloom on both old and new wood. Leaves are large, opposite, broadly ovate, glossy dark green, 4–8 inches (10–20 cm), with coarsely serrated margins.

Native Range

Native to the Pacific coastal forests and cliffs of central and southern Honshu, Japan, growing in moist, well-drained, humus-rich soils at low to moderate elevations near the sea. Long cultivated in Japan and China; introduced to European horticulture in the late 18th century and developed into hundreds of garden cultivars. Not native to North America.

Suggested Uses

Bigleaf mophead hydrangea is one of the most reliable and versatile deciduous shrubs for Pacific Northwest gardens, thriving in the region's naturally acidic soils and mild, moist summers. Outstanding as a shrub border specimen, foundation planting, container plant, and cut or dried flower plant. The large mophead flower clusters in blue, pink, or purple make a bold summer statement. Excellent combined with Hosta, Astilbe, Rodgersia, ferns, and Pieris in a partially shaded planting. Specify remontant cultivars for reliability after difficult winters. A Great Plant Pick for Pacific Northwest gardens.

How to Identify

Bigleaf hydrangea (Mophead Group) is identified by its large, opposite, broadly ovate, glossy dark green leaves 4–8 inches (10–20 cm) with coarsely serrated margins, and by its large, rounded flower heads 6–12 inches (15–30 cm) across composed almost entirely of sterile florets with four to five broad sepals. Flower color (blue in acid soil, pink in alkaline soil) is a useful contextual clue. Distinguished from the Lacecap Group by its solid, ball-shaped flower heads with no central fertile flowers visible; from H. arborescens by its opposite glossy leaves and soil pH-dependent flower color; from H. paniculata by its rounded (not conical) flower heads.

Appearance

Size & Dimensions

Height4' - 6'
Width/Spread4' - 6'

Reaches mature size in approximately 4 years

Colors

Flower Colors

blue
purple
pink

Foliage Colors

green

Fall Foliage Colors

no change

Bloom Information

Bloom Period

~6 weeks
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Summer
Bigleaf hydrangea blooms from mid-summer through early autumn, typically June through August in Pacific Northwest gardens, with dried flower heads persisting ornamentally through winter on many cultivars. Traditional cultivars bloom for four to six weeks on old wood; remontant cultivars may produce a second flush on new wood in late summer. Flower color shifts from initial tones toward green and then tan or rust as the season progresses, and dried heads retain interest through winter.

Detailed Descriptions

Flower Description

Blue to purple (acidic soil, pH below 6.0); pink to red (alkaline soil, pH above 7.0); large rounded mophead clusters 6–12 inches (15–30 cm) across of sterile florets

Foliage Description

Opposite, broadly ovate, 4–8 inches (10–20 cm), glossy dark green, coarsely serrated

Growing Conditions

Sun Requirements

Partial Shade
Full Shade
Requires 3-6 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 Range4.5 - 6.5(Acidic)
357912
Soil Types
loampeat
Drainage
moist

Water & Climate

Water Needs

High

Frost Tolerance

hardy

Time to Maturity

3–5 years

Care & Maintenance

Care Guide

Plant in partial shade to full sun in moist, well-drained, humus-rich, acidic to slightly acid soil. In Pacific Northwest gardens, bigleaf hydrangea performs best with morning sun and afternoon shade, or in bright dappled light. Consistent moisture is essential — mulch generously to retain soil moisture. For blue flowers: maintain soil pH below 6.0 and apply aluminum sulfate in early spring per package directions. For traditional cultivars, do not prune in autumn — remove only dead stems and spent flower heads in late winter (February–March), cutting stems to the first pair of plump buds. For remontant cultivars, light pruning is more forgiving. Protect from cold drying east winds and late spring frosts.

Pruning

For traditional old-wood-blooming cultivars: do not prune in autumn. In late winter (February–March), remove dead stems at the base and cut remaining stems to the first pair of visible, plump buds — typically 12–18 inches (30–45 cm) above the ground. If stems are winter-killed, cut to ground level; the plant will produce new growth but may not flower until the following year. For remontant cultivars: cut back by one-third in early spring for a compact, floriferous plant.

Pruning Schedule

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early spring

Maintenance Level

moderate

Container Growing

✓ Suitable for container growing

Minimum container size: 15 gallons

⚠️ Toxicity Warning

Toxic to pets and humans
Hydrangea macrophylla (bigleaf hydrangea) - Identification & Care Guide | PlantRef