• AGM plants

    AGM plants have been through a rigourous trial and assessment programme. They are:

    • Excellent for ordinary use in appropriate conditions
    • Available to buy
    • Of good constitution
    • Essentially stable in form & colour
    • Reasonably resistant to pests & diseases

Campanula glomerata 'Superba'

Clustered bellflower 'Superba'

AGM plants

AGM plants have been through a rigourous trial and assessment programme. They are:

  • Excellent for ordinary use in appropriate conditions
  • Available to buy
  • Of good constitution
  • Essentially stable in form & colour
  • Reasonably resistant to pests & diseases
Clustered bellflower 'Superba'

© � RHS 2002

  • Other common names Clustered bellflower 'Superba'

  • Genus Campanula may be annuals, herbaceous or evergreen perennials, with bell or star-shaped, often blue, flowers in late spring or summer

  • Family Campanulaceae / Campanulaceae

  • Species 'Superba' is a strong-growing rhizomatous perennial forming a wide colony of erect stems to 60cm, with oblong to ovate leaves and dense clusters of deep violet-purple, bell-shaped flowers 3cm in length

Characteristics

  • Foliage Deciduous

  • Habit Suckering

  • 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)
    Old hardiness ratings

    While we update our systems with the new hardiness ratings you may still see old hardiness ratings in your search results. These are denoted as 'Old'.

    • H1 - Requires heated glass
    • H2 - Requires unheated glass
    • H3 - Hardy outside in some regions of the UK
    • H4 - Hardy throughout the UK
    • H1 + H3 - Requires heated glass but may be grown outside in summer

    For full details of the hardiness ratings see

    see more

    H7

Colour

Sunlight

  • Full Sun

  • Partial Shade

  • Aspect South-facing or East-facing or West-facing or North-facing

  • Exposure Exposed or Sheltered

Soil

  • Chalk

    Loam

  • Chalk

    Chalk

  • MoistureMoist but well-drained

  • SoilLoam, Chalk

  • pHAlkaline, Neutral

Size

  • Ultimate height

    0.1-0.5 metres

  • Ultimate spread

    0.5-1 metres

  • Time to ultimate height

    2-5 years

How to grow

Cultivation Best grown in fertile, neutral to alkaline soil that is moist but well-drained, in partial shade or sun. No need to stake

Propagation Propagate by division in spring or autumn or take basal cuttings in winter

Suggested planting locations and garden types Flower borders and beds Underplanting of Roses and Shrubs Cut Flowers Cottage & Informal Garden Wildflower meadow

How to care

Pruning Cut back after flowering to encourage a second flush of flowers

Pests Damaged by slugs, snails and aphids

Diseases May be infected by a rust, powdery mildews and a leaf spot

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