Not the plant you're looking for? Search over 300,000 plants

Shrubs

Hibiscus syriacus double blue

A medium to large, deciduous shrub up to 4m tall with an upright habit. Lobed leaves appear in late spring and large, double blue flowers with conspicuous protruding tubes of stamens open in succession from midsummer into autumn

Save to My plants

Ultimate height

2.5–4 metres

Time to ultimate height

5–10 years

Ultimate spread

1.5–2.5 metres

Chalk

Clay

Loam

Sand

Moisture

Moist but well–drained, Well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

South–facing or West–facing or East–facing

Exposure

Sheltered

Hardiness
Hardiness ratings
All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets
H1a: under glass all year (>15C)
H1b: can be grown outside in the summer (10 - 15)
H1c: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20)

Botanical details

Family: Malvaceae
Native to the UK: No
Foliage: Deciduous
Habit: Bushy
Genus: Hibiscus can be deciduous or evergreen shrubs, trees, annuals or perennials, with simple or palmately lobed leaves and large, funnel-shaped flowers over a long flowering season
Name status: Unresolved

How to grow

Cultivation

Grows best in neutral to slightly acidic or slightly alkaline, humus-rich, moist but well-drained soil. Plant in a warm sheltered position in full sun to encourage flowering. Can also be grown in pots. Feed in spring, with a slow-release, high potash formula, such as rose food, and mulch in autumn to help maintain soil moisture levels and suppress weeds.

Propagation

Propagate by softwood cuttings in late spring, by semi-ripe cuttings in summer, or by layering in spring or autumn

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Patio and container plants
Coastal
Flower borders and beds
Wall side borders

Pruning

Very little pruning required, just prune away any broken or dead branches after flowering - pruning group 1.

Pests

May be susceptible to aphids, scale insects, mealybugs and glasshouse whitefly when grown under glass

Diseases

May be susceptible to honey fungus (rarely) and powdery mildews

Get involved

The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.