• 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

Picea pungens (Glauca Group) 'Koster'

Colorado spruce 'Koster'

Colorado spruce 'Koster'


  • Other common names Colorado spruce 'Koster'

  • Synonyms Picea kosteri 'Glauca'
    Picea pungens 'Koster Compacta'

  • Family Pinaceae

  • Genus Picea are evergreen trees with rigid, needle-like leaves arranged singly all round the shoots, and narrow, leathery-scaled cones borne near the ends of the shoots

  • Details 'Koster' is an evergreen conifer making a medium-sized tree of neat, conical habit, with prickly, vivid silvery-blue foliage


  • Foliage Evergreen

  • Habit Columnar/Upright

  • 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)




  • Full Sun

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

  • Exposure Exposed or Sheltered


  • Chalk


  • Chalk


  • Chalk


  • MoistureMoist but well-drained

  • SoilLoam, Clay, Sand

  • pHAcid, Neutral


  • Ultimate height 2.5-4 metres

  • Ultimate spread 1-1.5 metres

  • Time to ultimate height 20-50 years

How to grow

Cultivation Grow in moist but well-drained acidic soil. Shelter from cold drying winds

Propagation Propagate by grafting or semi-hardwood cuttings

Suggested planting locations and garden types Low Maintenance Architectural

How to care

Pruning No pruning required

Pests May be attacked by adelgids, aphids and conifer red spider mite

Diseases Generally disease free

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