• 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

Lithodora diffusa 'Grace Ward'

purple gromwell 'Grace Ward'

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
purple gromwell 'Grace Ward'

© RHS

  • Other common names purple gromwell 'Grace Ward'

  • Synonyms Lithospermum prostratum 'Grace Ward'

  • Family Boraginaceae

  • Genus Lithodora are evergreen shrubs or sub-shrubs, with 5-lobed blue or white flowers in summer

  • Details 'Grace Ward' is a low-growing or prostrate evergreen shrub forming a wide mat, to 15cm tall, with small, oblong, coarsely hairy leaves, and star-shaped, intense deep blue flowers 15mm wide in late spring and summer

Characteristics

  • Foliage Evergreen

  • Habit Mat forming

  • 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)

    H5

Colour

Sunlight

  • Full Sun

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

  • Exposure Exposed or Sheltered

Soil

  • Loam

    Loam

  • Sand

    Sand

  • MoistureWell-drained

  • SoilLoam, Sand

  • pHAcid, Neutral

Size

  • Ultimate height 0.1-0.5 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 2-5 years

How to grow

Cultivation Excellent for an open, sunny position with an acidic soil in a rock garden or raised bed

Propagation Propagate by semi-hardwood cuttings

Suggested planting locations and garden types City & Courtyard Gardens Coastal Cottage & Informal Garden Gravel Garden Rock Garden Patio & Container Plants

How to care

Pruning Pruning group 8

Pests Generally pest free

Diseases Generally disease free

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