• 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

Calycanthus occidentalis

California allspice

California allspice

© RHS 1997

  • Other common names California allspice

  • Synonyms Calycanthus macrophyllus

  • Family Calycanthaceae

  • Genus Calycanthus are deciduous shrubs with simple, aromatic leaves and solitary, fragrant flowers in summer

  • Details C. occidentalis is a large bushy shrub with rough-textured, dark green, ovate leaves and solitary deep red flowers to 5cm across, in summer

  • Plant range SW US

Characteristics

  • Foliage Deciduous

  • Habit Bushy

  • Fragrance Flower

  • 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)

    H6

Colour

Sunlight

  • Full Sun

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Clay

    Clay

  • Chalk

    Chalk

  • Sand

    Sand

  • Loam

    Loam

  • MoistureWell-drained, Moist but well-drained

  • SoilClay, Chalk, Sand, Loam

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 2.5-4 metres

  • Ultimate spread 2.5-4 metres

  • Time to ultimate height 10-20 years

How to grow

Cultivation Good for woodland or stream side positions

Propagation Propagate by seed or softwood cuttings

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

How to care

Pruning Pruning group 6

Pests Generally pest free

Diseases Generally disease free

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