• 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

Allamanda cathartica

golden trumpet

golden trumpet

© RHS 2002

  • Other common names golden trumpet

  • Family Apocynaceae

  • Genus Allamanda are evergreen shrubs, sometimes scrambling, with simple, often whorled leaves and terminal clusters of large trumpet-shaped flowers

  • Details A. cathartica is a vigorously climbing evergreen shrub with simple, whorled leaves and trumpet-shaped bright yellow flowers 12cm in length, borne in axillary or terminal cymes in summer and autumn

Characteristics

  • Foliage Evergreen

  • Habit Climbing

  • Toxicity Ingestion may cause severe discomfort

  • 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)

    H1B

Colour

Sunlight

  • Full Sun

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

  • Exposure Sheltered

Soil

  • Loam

    Loam

  • Sand

    Sand

  • MoistureMoist but well-drained

  • SoilLoam, Sand

  • pHAcid, Neutral

Size

  • Ultimate height 8-12 metres

  • Ultimate spread 2.5-4 metres

  • Time to ultimate height 10-20 years

How to grow

Cultivation Grow outdoors in moist but fertile soil in full sun in frost-free location. Under glass grow in loam-based potting compost in full sun

Propagation Propagate by seed or greenwood cuttings

Suggested planting locations and garden types Wall-side Borders Sub-tropical Patio & Container Plants

How to care

Pruning Pruning group 11 or pruning group 12

Pests Can get glasshouse red spider mite and glasshouse whitefly

Diseases Generally disease free

Did you find the information you were looking for?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now

Get involved

We're a UK charity established to share the best in gardening. We want to enrich everyone's life through plants, and make the UK a greener and more beautiful place.