Platycodon grandiflorus 'Astra Blue' (Astra Series)

RHS Plant Profile
balloon flower 'Astra Blue'

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balloon flower 'Astra Blue' RHS
Herbaceous Perennial
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A dwarf herbaceous perennial with narrow, mid-green leaves and large, star-shaped, violet-blue flowers opening from inflated, balloon-like buds all summer

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
1–2 years
Max Spread
0.1-0.5 metres
Max Height
0.1-0.5 metres

Growing Conditions

Clay Loam Sand
Moisture
Moist but well–drained
pH
Acid or Alkaline or Neutral

Position

Full sun Partial shade
Aspect
South–facing or North–facing or West–facing
Exposure
Exposed or 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
Campanulaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Genus
Platycodon are herbaceous perennials with neat, ovate leaves and terminal clusters of open bell-shaped flowers which open from large, balloon-shaped buds in late summer
Name Status
Accepted

How to Grow

Cultivation

Grow in deep, light, fertile, moist but well-drained soil in sun or semi-shade

Propagation

Propagate by seed sown in pots or in situ

Suggested planting locations and garden types

  • City and courtyard gardens
  • Cottage and informal garden
  • Rock garden
  • Gravel garden
  • Patio and container plants
  • Flower borders and beds
  • Garden edging
  • Underplanting of roses and shrubs

Pruning

Cut down to the base in autumn

Pests

May be susceptible to slugs and snails

Diseases

Generally disease-free