Climbing hydrangea

Climbing hydrangea: how do you recognise it?

Habit

Deciduous climber with aerial roots, up to 10–15 m; without support a broad, sprawling shrub.

Leaf

Opposite, 5–10 cm, round to oval with a heart-shaped base, finely toothed and glossy; yellow autumn colour.

Stems and bark

Reddish-brown stems with short aerial roots; old stems with peeling bark.

Flower

Flat heads (15–25 cm) with small flowers in the centre and large white outer flowers, June–July; fragrant.

Fruit

Small capsules; the dry flower heads hang on through winter.

Difference from ivy

Ivy is evergreen, with lobed leaves and green flowers in autumn.

Difference from hydrangea

The common hydrangea is a shrub, without aerial roots.

Flowering: June–July · Pruning: July–August

Identify by feature: Aerial roots and sucker pads

Looks like it, but isn’t

• Common ivy Hedera helix: evergreen, lobed leaves and green flowers in autumn. Difference from common ivy
• Hydrangea Hydrangea macrophylla: a shrub, without aerial roots. Difference from hydrangea

Why grow it?

• One of the few flowering climbers for a north- or east-facing wall.
• Large, white, fragrant flower heads in June–July, full of bees and hoverflies.
• Climbs by itself with aerial roots: no wires or trellis needed.
• Yellow autumn colour and attractive peeling bark in winter.
• A dense green wall where birds like to nest.

Climbing hydrangea: where does it grow best?

• Partial shade to shade: ideal for a north- or east-facing wall, or in an old tree.
• Moist, humus-rich soil; the foot of a wall is often dry, so give it extra water there.
• A sturdy wall, fence or tree trunk: it becomes heavy and can climb to 10–15 m.
• Keep it away from gutters, roof tiles and window frames; on a sound, well-pointed wall it does little harm.

Light

Partial shade or shade

Legal basis

Any garden soil

Moisture

Moist to wet

Size

10 m tall, 3 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Hydrangea: A flowering shrub for the same shady, moist foot of the wall.
• Lesser periwinkle: An evergreen ground cover that keeps the soil at the foot of the wall cool.
• Hosta: Large, handsome leaves in the shade at the foot of the climber.

Good and bad companions

Goes well with

• Can climb into old, large trees: english oak, scots pine, sycamore, large-leaved lime

Climbing hydrangea: when and how to plant it?

1. Plant a pot-grown plant in spring or autumn.
2. Plant 30–50 cm from the wall, where the soil is less dry, and lean the plant towards the wall.
3. Mix compost or leaf mould into the planting soil and water generously.
4. For the first few years, tie the first shoots to the wall or to a cane until the aerial roots get a grip.

Care

Watering

In dry spells for the first few years, and in dry summers later on too: at the foot of a wall the soil dries out quickly.

Feeding

A little compost or organic fertiliser in spring.

Mulching

A layer of leaf mould or compost over the roots keeps them cool and moist.

Patience

For the first 2–3 years it grows slowly and does not flower yet: that is normal.

Tip: Gardeners say of climbers: the first year they sleep, the second year they creep, the third year they leap. With climbing hydrangea it is true: be patient.

Climbing hydrangea: when to prune it?

Pruning months: July–August.

When: After flowering, in July–August.

How:

• Little needed: cut back branches that stick out too far from the wall or grow towards gutters and windows.
• It flowers on short side shoots of older wood: so don’t prune in winter or spring, or you will cut off the flowers.
• Rejuvenate a plant that has become too thick and heavy over a few years, removing a few old stems each time.

Caution: Before you prune, check that no birds are nesting in the dense climber.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Layering

In spring, lay a low stem on the ground and cover it; it roots easily.

Cuttings

In summer, take cuttings of 10–15 cm and root them in a pot under plastic.

Climbing hydrangea: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Fully hardy.
• In winter the dry flower heads and the reddish-brown, peeling bark decorate the bare wall.

Diseases and pests

• No flowers: A young plant does not flower for the first few years, and winter pruning removes the flowers. Be patient and only prune after flowering.
• Dry roots: Limp, brown leaves in summer because of dry soil at the foot of the wall. Water and mulch.
• Aphids: Aphids on the young shoots in spring; natural predators usually deal with them.
• Coming loose: Long branches that hang down or come away from the wall. Tie them in or cut them back after flowering.

Through the year

• March: Planting; compost or mulch over the roots.
• April: It comes into leaf: guide young shoots against the wall.
• May: Water the foot of the wall in dry spells.
• June: Flowering begins: white, fragrant flower heads.
• July: Prune after flowering: cut back branches that stick out.
• August: Finish pruning; take cuttings.
• October: Yellow autumn colour; planting is possible.
• December: Dry flower heads and reddish-brown bark.

What can you use it for?

Garden and landscape

Flowering climber for a shady north- or east-facing wall, or in an old tree.

For wildlife

Bees and hoverflies on the flowers; nesting site for birds.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Hoverflies

Open flowers for hoverflies; many of their larvae eat aphids.

Birds

Berries, seeds or insects as food, or a place to nest.

Did you know?

• One of the few flowering climbers for a north-facing wall. It grows slowly for the first few years; after that it takes off.
• The large white outer flowers are sterile: they lure insects to the small, fertile flowers in the centre.
• In its homeland it climbs high into the trees in the forests.
• In its homeland, the forests of Japan, Korea and the island of Sakhalin, it climbs high into the trees with its aerial roots.
• The large white outer flowers are sterile: they act as a lure for insects, which pollinate the small fertile flowers in the centre.