Hibiscus syriacus Ultramarine ('Minultra'PBR)

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rose of Sharon [Ultramarine]

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rose of Sharon [Ultramarine] RHS
rose of Sharon [Ultramarine] RHS

Other common names

rose of Sharon 'Minultra'

Synonyms

Hibiscus syriacus 'Minultra'PBR

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Shrubs
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A vigorous upright shrub up to 3m high, with deciduous, three-lobed green leaves, and single deep violet-blue flowers, 8-10cm across, with dark red centres and veins and cream stamens, from midsummer to early autumn; honeybees and bumblebees may visit for pollen

Position

Full sun

Soil Types

Loam

Max Height

2.5-4 metres

Max Spread

1.5-2.5 metres

Size

Time to Maturity
5–10 years
Max Spread
1.5-2.5 metres
Max Height
2.5-4 metres

Growing Conditions

Loam
Moisture
Moist but well–drained
pH
Neutral

Position

Full sun
Aspect
South–facing or West–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)
H5

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family
Malvaceae
Native to GB/Ireland
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
Trade

How to Grow

Cultivation

Grow in neutral, humus-rich, moist but well-drained soil in full sun, in a warm position such as a south-facing or west-facing wall to encourage flowering, and protect roots in winter with an organic mulch

Propagation

Propagate by softwood cuttings in late spring, by semi-ripe cuttings in summer, or by layering in spring or autumn; propagation for resale is prohibited without a licence

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Low Maintenance
  • Flower borders and beds
  • Wall side borders

Pruning

Pruning group 1 (little or no pruning of trees and shrubs)

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