• 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

Allium caesium

light blue garlic

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
light blue garlic

© RHS

  • Other common names light blue garlic

  • Synonyms Allium urceolatum

  • Family Alliaceae

  • Genus Allium are bulbous herbaceous perennials with a strong onion or garlic scent, linear, strap-shaped or cylindrical basal leaves and star-shaped or bell-shaped flowers in an umbel on a leafless stem

  • Details A. caesium is a bulbous perennial to 50cm, with very slender leaves and dense umbels 2cm in width, composed of green-veined, violet-blue flowers in late spring and early summer

  • Plant range Siberia to C. Asia, Pamir and Tien Shan Mts

Characteristics

  • Foliage Deciduous

  • Habit Tufted

  • Toxicity

  • 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 West-facing or East-facing

  • Exposure Sheltered

Soil

  • Sand

    Sand

  • Clay

    Clay

  • Chalk

    Chalk

  • Loam

    Loam

  • MoistureWell-drained, Moist but well-drained

  • SoilSand, Clay, Chalk, Loam

  • pHAcid, Alkaline, Neutral

Size

  • Ultimate height 0.1-0.5 metres

  • Ultimate spread 0-0.1 metre

  • Time to ultimate height 2-5 years

How to grow

Cultivation Easy to grow in fertile well-drained soil. Add grit to clay soils to improve drainage

Propagation Propagate by seed sown in containers in a cold frame when ripe or in the spring or remove offsets in autumn

Suggested planting locations and garden types Flower borders and beds Cut Flowers Low Maintenance City & Courtyard Gardens Coastal Cottage & Informal Garden Gravel Garden Mediterranean Climate Plants Rock Garden Wildlife Gardens

How to care

Pruning No pruning required

Pests Susceptible to onion fly

Diseases Susceptible to onion white rot and a downy mildew

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