• AGM plants

    AGM plants have been through a rigorous 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

Chelone obliqua

twisted shell flower

  • Other common names twisted shell flower

  • Family Plantaginaceae

  • Genus Chelone are herbaceous perennials with undivided, paired leaves and short terminal spikes of showy, 2-lipped, tubular flowers opening from late summer to early autumn

  • Details C. obliqua is an erect perennial to 60cm tall, with prominently veined and toothed leaves, and compact spikes of dusky deep pink or purple flowers 2cm long

  • Plant range USA

Characteristics

  • Foliage Deciduous

  • Habit Bushy

  • 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

Sunlight

  • Full Sun

  • Partial Shade

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

  • Exposure Sheltered

Soil

  • Clay

    Clay

  • Loam

    Loam

  • MoisturePoorly-drained, Moist but well-drained

  • SoilClay, Loam

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 0.5-1 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 2-5 years

How to grow

Cultivation Grow in deep fertile, moist soil in partial shade or sun. Tolerant of heavy clay soil, may also be grown in a bog garden; apply a deep mulch of organic matter in mid-spring

Propagation Propagate by seed sown in containers in a cold frame in early spring; by division in spring; root soft tip cuttings in late spring or early summer

Suggested planting locations and garden types Flower borders and beds Cottage & Informal Garden

How to care

Pruning Deadhead flower spikes as they fade

Pests Susceptible to damage from slugs and snails

Diseases Generally disease free

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