• 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

Washingtonia × filibusta

Washington palm

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
Washington palm

© RHS 2002

  • Other common names Washington palm
    Californian washingtonia

    cotton palm
    desert fan palm
    northern washingtonia

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  • Family Arecaceae

  • Genus Washingtonia are large evergreen palms with stout solitary trunks bearing long-stalked, rounded leaves palmately divided into linear segments, and large, arching panicles of flowers, followed by small, berry-like black fruits

  • Details W. filifera is a tree-like palm with a stout trunk to 20m, and arching, narrow-lobed, fan-shaped leaves 2-3m in length; flowers creamy-white, in large panicles

  • Plant range S. California, W. Arizona, Mexico

Characteristics

  • Foliage Evergreen

  • 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)

    H1C

Colour

Sunlight

  • Partial Shade

  • Aspect East-facing or North-facing

  • Exposure Sheltered

Soil

  • Chalk

    Loam

  • MoistureWell-drained

  • SoilLoam

  • pHAcid, Neutral

Size

  • Ultimate height Higher than 12 metres

  • Ultimate spread 2.5-4 metres

  • Time to ultimate height 20-50 years

How to grow

Cultivation Grow under glass in a loam-based compost with equal parts added pulverised bark and organic matter, in bright light but with protection from the sun. Water moderately and provide moderate humidity when in growth and apply a liquid fertiliser monthly during the summer. Water sparingly in winter

Propagation Propagate by seed sown at not less than 24ºC

Suggested planting locations and garden types Architectural Patio & Container Plants

How to care

Pruning No pruning required

Pests May be attacked by glasshouse red spider mite and scale insects

Diseases Generally disease free

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