• 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

Pinus coulteri

big-cone pine

big-cone pine

© RHS 1999

  • Other common names big-cone pine
    Coulter's pine

    Coulter pine

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  • Family Pinaceae

  • Genus Pinus can be shrubs or large, evergreen trees, some species with attractive bark, developing an irregular outline with age and bearing long needle-like leaves in bundles of 2, 3 or 5; conspicuous cones may fall or remain on the tree for years

  • Details P. coulteri is a large evergreen tree with a broad, open crown. Stout shoots bear thick, blue-grey needles up to 35cm long, in bundles of three. Massive pale brown cones to 30cm long, with a spine on each scale

  • Plant range W California to 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)

    H4

Colour

Sunlight

  • Full Sun

  • Aspect South-facing

  • Exposure Exposed or Sheltered

Soil

  • Chalk

    Sand

  • Chalk

    Clay

  • Chalk

    Chalk

  • Chalk

    Loam

  • MoistureWell-drained

  • SoilSand, Clay, Chalk, Loam

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height Higher than 12 metres

  • Ultimate spread wider than 8 metres

  • Time to ultimate height more than 50 years

How to grow

Cultivation Grow in any well drained soil in full sun

Propagation Propagate by seed sown in containers in a cold frame in late winter. Retain in pots for at least two years

Suggested planting locations and garden types Coastal Architectural

How to care

Pruning Generally no pruning required. Remove competing leaders and, on older trees, crown lift by removing some of the lower branches

Pests Pine adelgid and sawfly may occur

Diseases May be affected by honey fungus, various needle cast diseases and tree rust

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