Climbing hydrangea

Sun

Partial shade is ideal; tolerates full shade but flowers less. Full sun is suitable in cool climates if the soil stays moist; avoid hot afternoon sun in warmer regions.

Water

Keep the root zone consistently moist but not waterlogged, especially during establishment and beneath rain-sheltered walls. Water established plants deeply during prolonged dry spells.

Soil

Humus-rich, moisture-retentive but well-drained soil. Tolerates acidic to mildly alkaline conditions; struggles in dry, shallow soil or stagnant wet ground.

Height

30-50 ft (9-15 m)

Spread

10-20 ft (3-6 m)

Flowers

Late spring to early summer; broad white lacecap heads with small fertile flowers surrounded by larger, showy sterile florets.

Foliage

Opposite, heart-shaped to broadly oval, toothed green leaves, often turning yellow in autumn. Older stems develop peeling cinnamon-brown bark.

Growth

Slow for the first few years, then moderate to vigorous once established.

Care needed

Medium

• Plant away from the driest strip immediately beside a wall, and angle the shoots towards their support.
• Tie young stems loosely to a sturdy framework until their aerial rootlets take hold.
• Water deeply during dry weather, particularly through the first two or three growing seasons.
• Apply 2-3 in (5-8 cm) of leaf mould or compost each spring, keeping it clear of the main stems.
• Feed lightly in spring only if growth is weak; avoid heavy nitrogen feeding.
• Use sound masonry or a substantial support, and keep stems away from gutters, roof tiles and painted timber.

Pruning. Prune just after flowering, shortening outward-growing shoots and removing dead or unwanted stems; flowers form on older wood. If major reduction is necessary, spread it over several years and expect fewer flowers.

Early spring

Plant while the soil is workable, check young ties and remove clearly dead or damaged stems.

Spring

Mulch the root area with compost or leaf mould and feed lightly only if needed.

Late spring

Guide new shoots towards their support and check moisture beneath walls and eaves.

Summer

After flowering, shorten projecting shoots and clear growth from windows and gutters.

Summer

Water deeply during dry spells and take semi-ripe cuttings if you want more plants.

Autumn

Layer a low, flexible shoot into the soil and inspect the support before winter storms.

• Cover a tall, shaded masonry wall with foliage and white early-summer flowers.
• Train over a substantial pergola where its hanging flower heads can be seen from below.
• Use against a woodland-edge wall with ferns and hostas beneath it.
• Grow along a strong boundary wall to soften hard surfaces, leaving room for its mature width.

Garden styles it suits: Woodland, English country, Traditional, Secret garden, White garden and Romantic rose garden.

Plant it with: Hostas, Japanese painted ferns, Soft shield ferns, Hellebores, Siberian bugloss and Solomon's seal.

Wildlife: The small fertile flowers provide pollen and nectar for bees and other insects. Dense mature growth offers shelter and possible nesting sites for birds; check for active nests before pruning.

• Little or no flowering: young plants may take several years to bloom. Avoid heavy shade, excessive nitrogen and pruning before flowering.
• Wilting or scorched leaf edges: check for dry soil beneath the surface, water deeply and mulch; provide protection from hot afternoon sun.
• Hydrangea scale: check leaf undersides and stems for white egg masses; remove small infestations by hand and prune out heavily affected shoots.
• Leaf spots or powdery mildew: improve airflow, water at soil level and clear fallen diseased leaves; minor late-season spotting rarely needs treatment.

Toxic if eaten by cats, dogs, horses or people. Leaves and flower buds contain cyanogenic compounds, and other parts should also be treated as unsafe to eat. Ingestion usually causes vomiting, diarrhoea or abdominal discomfort; serious poisoning is uncommon but larger amounts can be dangerous. Contact a veterinarian or poison service if ingestion is suspected.

• Japanese hydrangea vine (Schizophragma hydrangeoides)

  Each showy sterile flower has one large, usually heart-shaped white bract; climbing hydrangea has several petal-like sepals around each sterile flower.

• Seemann's hydrangea (Hydrangea seemannii)

  An evergreen climber with leathery leaves that remain through winter in suitable climates; climbing hydrangea loses its thinner leaves in autumn.

Hydrangea comes from Greek words meaning water vessel, referring to the seed capsules, while petiolaris refers to the conspicuous leaf stalks.

Propagation. Layer a low shoot in spring or autumn, leaving it attached until well rooted, or take semi-ripe cuttings in summer. Rooting and establishment can be slow.

Accepted botanical name

Hydrangea petiolaris Hydrangea anomala subsp. petiolaris is an older name for Hydrangea petiolaris.

Native range

Japan, Korea, Kuril Is. and Sakhalin.

Measured

Average height 1780 cm.

Sources: GBIF (CC BY 4.0) and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.