Syrian hibiscus

Syrian hibiscus: how do you recognise it?

Habit

Upright shrub of 2–3 m with stiff, rising branches; also grown as a small standard.

Leaf

Alternate, 5–10 cm, diamond-shaped, often three-lobed, coarsely toothed; appears late in spring.

Bark

Greyish-brown, with upright branches.

Flower

Large trumpet flowers (6–10 cm) in white, pink, purple or blue, often with a dark centre, from August to October.

Fruit

Hairy capsules that last through the winter.

Difference from Chinese hibiscus

Chinese hibiscus (Hibiscus rosa-sinensis) is evergreen and not hardy.

Flowering: August–September · Pruning: March

Identify by feature: Palmate leaves · Purple or blue flowers

Looks like it, but isn’t

• Chinese hibiscus (Hibiscus rosa-sinensis): evergreen and not hardy.

Why grow it?

• Late flowers from August to October, when few other shrubs are in bloom.
• Large, exotic-looking flowers in white, pink, purple or blue.
• Bumblebees and bees crawl deep into the flowers.
• Stays compact and upright: suitable for a small garden, also as a small standard.

Syrian hibiscus: where does it grow best?

• Full sun; in shade it hardly flowers.
• Any well-drained soil that does not dry out in summer; no wet feet in winter.
• A warm, sheltered spot, for instance in front of a south-facing wall, gives the best flowering.
• Allow for 2–3 m tall and about 2 m wide.

Light

Full sun

Legal basis

Any garden soil

Moisture

Normal

Size

3 m tall, 2 m wide

Hardiness

Throughout Belgium, no protection needed

Goes well with

• Panicled hydrangea: Also flowers in late summer, and is likewise pruned in March.
• English lavender: A sunny, fragrant underplanting that is already in flower before the hibiscus starts.
• Michaelmas daisy: Flowers in September–October at its feet and attracts the same late bees and butterflies.

Good and bad companions

Best kept away from

• Do not plant under the dense crown of these trees: norway spruce, european silver fir, nordmann fir, douglas fir, yew, horse chestnut, norway maple, sycamore

Syrian hibiscus: when and how to plant it?

1. Plant preferably in spring (April–May): it will then root well before its first winter.
2. Dig a generous planting hole and mix in some compost.
3. Plant at the same depth as in the pot and firm the soil well.
4. Water generously and keep the soil moist during the first year.

Care

Watering

In dry spells in the first year, and in dry summers later on too: otherwise it drops its buds.

Feeding

A little compost or organic fertiliser in spring.

Mulching

A layer of compost or bark keeps the soil cool and moist in summer.

Late leafing

It stays bare until May: don’t prune it or dig it up because it looks dead in April.

Tip: Want large flowers? In March, cut every shoot from last year back to 2–3 buds. Prefer a natural shrub with many smaller flowers? Then barely prune at all.

Syrian hibiscus: when to prune it?

Pruning months: March.

When: End of winter (March).

How:

• It flowers on new wood: cut last year’s shoots back to 2–3 buds for fewer but larger flowers.
• For a natural shape, prune only lightly: remove dead, weak and crossing branches.
• Keep a small standard in shape by shortening the crown every March.

Caution: Don’t prune too late in spring: it needs the whole season to grow new shoots that carry flower buds.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Cuttings

In July, take semi-ripe cuttings of 10–15 cm and root them in a pot of gritty compost, under glass or plastic.

Syrian hibiscus: how does it get through the winter?

Hardy throughout Belgium: no protection needed.

• Hardy in Belgium and the Netherlands; young plants are a little more tender in their first winter: mulch over the roots.
• The capsules stay on the shrub in winter; the bare branches look dead until May.

Diseases and pests

• Bud drop: The buds fall before they open, usually because of drought. Water in dry summers and mulch the soil.
• Aphids: Aphids on the young shoots and buds in early summer. Let ladybirds do their work or hose them off.
• Late leafing: It looks dead in April. Wait until late May, then scratch a twig: if it is green under the bark, it is alive.
• Few flowers: Usually too much shade or too cold a spot. Give it the sunniest, warmest place in the garden.

Through the year

• March: Pruning: shorten last year’s shoots.
• April: Planting; don’t panic if it is still bare.
• May: It comes into leaf; mulch.
• June: Keep an eye on aphids.
• July: Water in dry spells; take cuttings.
• August: Flowering begins.
• September: Full flower, with bumblebees in the blooms.
• October: Last flowers.

What can you use it for?

Garden and landscape

Late-summer flowers, when little else is in bloom; also as a small standard.

For wildlife

Bumblebees crawl deep into the flowers.

Good for wildlife

Bumblebees

Nectar and pollen for bumblebees, also from deep flowers and early in spring.

Bees

Nectar and pollen for honeybees and wild bees.

Did you know?

• It does not leaf out until May: don’t panic if it still looks dead in April.
• The name syriacus is a mistake: it was thought to come from Syria, where it had long been grown in gardens, but it comes from East Asia.
• It is the national flower of South Korea.
• Despite the name syriacus it does not come from Syria but from East Asia. Linnaeus believed it was Syrian because it was grown in gardens there.
• It is the national flower of South Korea, where it is called mugunghwa, the ‘eternal flower’, because it keeps blooming for months.