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Hydrangea paniculata

Panicle hydrangea

Hydrangeaceae

Japan, southern and eastern China, Korea, and Sakhalin in the Russian Far East

Attracts Pollinators Attracts Butterflies Fragrant (light)Container Friendly

SunFull Sun – Part Shade

WaterMedium

HardinessZones 3–8

Overview

Hydrangea paniculata is a deciduous shrub or small multi-stemmed tree growing 8-15 feet (2.4-4.5 m) tall and 6-12 feet (1.8-3.6 m) wide, with untrained specimens in old gardens reaching 25 feet (7.5 m). Leaves are opposite or in whorls of three, ovate to elliptic, 3-6 inches (7-15 cm) long, with serrate margins and coarse hairs on both surfaces. Conical panicles 6-18 inches (15-45 cm) long open from early July to September, mixing small fertile flowers about 0.1 inch (3 mm) across with sterile ray florets 0.8-1.2 inches (2-3 cm) wide. Panicles open greenish-white, hold white for three to five weeks, then flush pink to rose as night temperatures fall, drying to tan by November. Flower buds form on shoots produced in the current season, so a hard winter or a late-winter cut leaves the coming bloom intact. Soil pH has no effect on flower colour. Stems bend or break under saturated panicles after heavy rain, particularly on plants cut hard the previous spring. Foliage and buds contain cyanogenic glycosides and cause vomiting and diarrhoea in dogs, cats, horses, and people. Hardy in USDA zones 3-8.

Native Range

Hydrangea paniculata is native to Japan, southern and eastern China, Korea, and Sakhalin in the Russian Far East. It grows on open mountain slopes, forest margins, and rocky stream banks between 1,300 and 6,600 feet (400-2,000 m). Escapes from cultivation are recorded along woodland edges across New England and the mid-Atlantic states.

Suggested Uses

Planted as a hedge at 5-6 foot (1.5-1.8 m) spacing, as a border shrub, and as a standard trained to a single trunk. Cut stems are used fresh in mid-summer and dried from the tan stage in autumn. Container plants take 15 gallons (57 L) or more of root volume and daily watering in summer heat.

How to Identify

Inflorescences are elongated cones rather than the flat corymbs or rounded mopheads of other cultivated hydrangeas, with the axis clearly longer than wide. Leaves sit opposite or in whorls of three on the same plant, a pattern absent in H. macrophylla and H. arborescens. Second-year stems carry pale brown bark that peels in narrow strips, and the pith is white and solid. Dried panicles hold their shape on the plant through winter.

Appearance

Size & Dimensions

Height8' - 15'

Width/Spread6' - 12'

Reaches mature size in approximately 8 years

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~10 weeks

Summer Fall

Panicles open from early July in USDA zone 7 and from mid-July in zone 4, with colour held into late September. A single panicle passes through greenish-white, white, pink, and tan over eight to twelve weeks. Because flower buds form on current-season shoots, bloom follows even after stems are cut to 12 inches (30 cm) in late winter. Plants in fewer than four hours of direct sun carry panicles about half the length of those in full sun.

Detailed Descriptions

Flower Description

greenish-white opening to white, ageing pink to rose then tan

Foliage Description

medium to dark green, turning yellow before leaf drop

Growing Conditions

Sun Requirements

SunFull Sun SunPartial Shade

Requires 4-8 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

loam clay sand silt

Drainagemoist

Water & Climate

Water Needs

Medium

Frost Tolerance

hardy

Time to Maturity

5-8 years

Care & Maintenance

Care Guide

Four to eight hours of direct sun daily carries full panicle size, with afternoon shade reducing leaf scorch where summer temperatures pass 90 F (32 C). Soil is moisture-retentive loam at pH 5.0-7.5; unlike H. macrophylla, panicle colour does not shift with soil pH or aluminium availability. Water use is about 1 inch (2.5 cm) per week, and leaves wilt within two days of the root zone drying out. A single spring application of balanced granular fertiliser at 1 pound per 100 square feet (0.5 kg per 9 sq m) covers the season; higher nitrogen produces soft stems that bend under the panicles. Powdery mildew, leaf spot caused by Cercospora spp., and aphids occur in crowded plantings with restricted air movement.

Pruning

Cutting is done from late winter to early spring before bud break, because flowers form on shoots grown in the current season. Stems are shortened by one third, or cut to a framework 12-24 inches (30-60 cm) tall for larger panicles on fewer stems. Hard cutting produces long, soft shoots that bend under the flower heads, so a lighter cut leaving 24-36 inches (60-90 cm) of old wood holds the stems upright. Dried panicles left over winter come off with the spring cut.

Pruning Schedule

winterearly spring