• AGM plants

    AGM plants have been through a rigourous 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

Brunnera macrophylla 'Jack Frost' (PBR)

Siberian bugloss 'Jack Frost'

AGM plants

AGM plants have been through a rigourous 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
Siberian bugloss 'Jack Frost'

© � RHS

  • Other common names Siberian bugloss 'Jack Frost'

  • Genus Brunnera are rhizomatous herbaceous perennials with large, ovate or heart-shaped basal leaves and sprays of small bright blue flowers in spring

  • Family Boraginaceae / Boraginaceae

  • Species 'Jack Frost' is a perennial grown for its large, heart-shaped silver leaves edged and veined with green, and sprays of small blue flowers in spring

Characteristics

  • Foliage Deciduous

  • 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)
    Old hardiness ratings

    While we update our systems with the new hardiness ratings you may still see old hardiness ratings in your search results. These are denoted as 'Old'.

    • H1 - Requires heated glass
    • H2 - Requires unheated glass
    • H3 - Hardy outside in some regions of the UK
    • H4 - Hardy throughout the UK
    • H1 + H3 - Requires heated glass but may be grown outside in summer

    For full details of the hardiness ratings see

    see more

    H6

Colour

Sunlight

  • Full Shade

  • Partial Shade

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

  • Exposure Sheltered

Soil

  • Chalk

    Sand

  • Chalk

    Clay

  • Chalk

    Chalk

  • Chalk

    Loam

  • MoistureMoist but well-drained

  • SoilSand, Clay, Chalk, Loam

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height

    0.1-0.5 metres

  • Ultimate spread

    0.5-1 metres

  • Time to ultimate height

    2-5 years

How to grow

Cultivation Best grown in moderately fertile, humus-rich soil that is moist but well-drained. A cool site in partial shade or shade is preferred

Propagation Propagate by division in early spring or take root cuttings in winter

Suggested planting locations and garden types Banks and Slopes Flower borders and beds Underplanting of Roses and Shrubs Ground Cover Cottage & Informal Garden

How to care

Pruning No pruning required

Pests Generally pest free

Diseases Generally disease free

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