• 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

Buddleja davidii 'Black Knight'

butterfly bush 'Black Knight'

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
  • Other common names butterfly bush 'Black Knight'

  • Family Scrophulariaceae

  • Genus Buddleja can be evergreen or deciduous shrubs, occasionally trees or scrambling climbers with simple leaves and panicles of small, tubular fragrant flowers

  • Details 'Black Knight' is a vigorous large deciduous shrub to 3m, with somewhat arching growth and lance-shaped leaves, whitish beneath. Flowers scented, deep purple, in elongated panicles at tips of current year's growth

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 South-facing or East-facing or West-facing

  • Exposure Exposed or Sheltered

Soil

  • Loam

    Loam

  • Chalk

    Chalk

  • Sand

    Sand

  • Clay

    Clay

  • MoistureWell-drained, Moist but well-drained

  • SoilLoam, Chalk, Sand, Clay

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 2.5-4 metres

  • Ultimate spread 2.5-4 metres

  • Time to ultimate height 5-10 years

How to grow

Cultivation Buddleja perform best when grown in a sunny, well-drained situation

Propagation Propagate by semi-hardwood cuttings

Suggested planting locations and garden types Drought Resistant Flower borders and beds Low Maintenance Cottage & Informal Garden Wildlife Gardens

How to care

Pruning Pruning group 6

Pests Can get capsid bug, caterpillars, leaf and bud eelworms, aphids and glasshouse red spider mite

Diseases May suffer from a virus

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