Panicled hydrangea

Panicled hydrangea: how do you recognise it?

Habit

Upright, later broad shrub of 2–4 m with sturdy, woody branches; also sold as a standard.

Leaf

Opposite or in whorls of three, 7–15 cm, oval with a pointed tip, toothed, dull green and somewhat rough.

Bark

Brown, woody branches; old stems with peeling bark.

Flower

Cone-shaped heads (15–30 cm) of small fertile flowers and large, sterile, white florets, from July to September; they turn pink or red and stay on as dried flowers.

Fruit

Small capsules; the dry flower heads last through the winter.

Difference from hydrangea

The common hydrangea has mophead or lacecap flowers in pink or blue and glossy leaves, and flowers on last year’s wood.

Flowering: July–September · Pruning: March

Looks like it, but isn’t

• Hydrangea Hydrangea macrophylla: mophead or lacecap flowers in pink or blue and glossy leaves; flowers on last year’s wood. Difference from hydrangea

Why grow it?

• Reliable flowering from July to September, year after year.
• Easier than the common hydrangea: prune in March, and no frost damage to the flower buds.
• Grows in sun and partial shade, on acid and chalky soil alike.
• The flower heads change from white to pink and stay attractive as dried flowers into the winter.

Panicled hydrangea: where does it grow best?

• Sun to partial shade; in full sun it flowers most freely, provided the soil does not dry out.
• Any good garden soil, acid or chalky, ideally rich in humus and moisture-retentive.
• Allow 2–2.5 m width; compact cultivars stay around 1 m.
• Lovely as a specimen, in a border, as an informal hedge or, for compact cultivars, in a large pot.

Light

Sun or partial shade

Legal basis

Any garden soil

Moisture

Normal

Size

3 m tall, 2.5 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Hydrangea: Flowers from June, the panicled hydrangea from July: together they flower from June into autumn.
• Yew: A dark green hedge as a backdrop makes the white flower heads glow.
• Ornamental grasses: Airy stems next to the heavy flower heads, and both look good into winter.
• Butterfly bush: Flowers at the same time, in the same sunny spot, and draws butterflies into the border.

Good and bad companions

Goes well with

• Suits the woodland edge or the light shade of: ginkgo, box elder, ash, honey locust, field maple, silver maple

Panicled hydrangea: when and how to plant it?

1. Plant in autumn or spring, root-balled or from a pot.
2. Dig a generous planting hole and mix in compost or leaf mould.
3. Plant at the same depth as in the pot and firm the soil well.
4. Water thoroughly straight away and keep the soil moist during the first year; a layer of mulch helps.

Care

Watering

Water generously in dry spells, especially in full sun and in a pot; limp leaves are a sign of thirst.

Feeding

Some compost or organic fertiliser in spring; not too much nitrogen, or the branches go floppy.

Faded flower heads

Leave them until spring: they look good in winter and are removed with the pruning in March.

Support

Large flower heads can bend over after rain. Do not prune too hard, or choose a cultivar with sturdy stems.

Tip: For a small garden or a pot, choose a compact cultivar such as ‘Bobo’. ‘Limelight’ flowers lime-green, ‘Vanille Fraise’ turns from white to strawberry red and ‘Kyushu’ has airy heads with plenty of fertile flowers for insects.

Panicled hydrangea: when to prune it?

Pruning months: March.

When: End of winter (March).

How:

• It flowers on new wood: cut last year’s stems back to 2–3 pairs of buds.
• The harder you prune, the larger but fewer the flower heads; prune less hard and you get more, smaller heads on sturdier stems.
• On an older shrub, also cut a few weak or dead stems off at the base.

Caution: Do not confuse it with the common hydrangea: that flowers on last year’s wood and is only pruned lightly. The panicled hydrangea, on the other hand, can be cut back firmly in March.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Softwood cuttings

In June–July, take tip cuttings of 10–15 cm from non-flowering shoots, remove the lower leaves and root them in moist cutting compost.

Layering

In summer, bend a low branch to the ground, cover it with soil and sever it the following spring.

Panicled hydrangea: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Very hardy; because it flowers on new wood, even late frost does not cost you the flowers.
• Leave the dry flower heads on: with frost or snow they make a lovely winter picture.

Diseases and pests

• Drooping branches: After heavy rain, the large flower heads sometimes hang down to the ground. Prune less hard so the stems become sturdier, or tie the shrub in loosely.
• Limp or scorched leaves: Too dry, especially in full sun or in a pot. Water generously and mulch the soil.
• Few flowers: Usually too much shade, or no pruning, so the shrub makes lots of thin twigs. Give it more light and prune every year in March.
• Aphids: Aphids on the young shoots in spring; natural predators usually deal with them.

Through the year

• March: Prune: last year’s stems back to 2–3 pairs of buds; add compost.
• April: Planting; new shoots appear.
• June: Water in dry spells; flower buds appear.
• July: Flowering begins: white heads; take tip cuttings.
• August: Full flower; bees and hoverflies on the small fertile flowers.
• September: The flower heads turn pink to red.
• October: Planting; leave the dry flower heads on.
• December: Dry flower heads as winter interest.

What can you use it for?

Garden and landscape

Reliable summer-flowering shrub, even in full sun; lovely as a specimen, in a border or as a standard.

For wildlife

The small fertile flowers in the head attract bees and hoverflies.

Did you know?

• Its colour does not depend on the soil as in the common hydrangea: the white heads turn pink by themselves as the nights grow cooler.
• The large white ‘flowers’ on the head are sterile: they attract insects to the small fertile flowers in between.
• There are dozens of cultivars, from compact shrubs of 1 m to shrubs of 4 m.