• 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

Alliaria petiolata

Jack-by-the-hedge

  • Other common names Jack-by-the-hedge
    garlic mustard

  • Synonyms Sisymbrium alliaria
    Alliaria officinalis

  • Family Brassicaceae

  • Genus Alliaria can be annuals, biennials or perennials, with garlic-scented, ovate or heart-shaped leaves and racemes of small, white, 4-petalled flowers in spring

  • Details A. petiolata is a hairy biennial herb, which can be variable in height; is usually unbranched and bears heart to kidney-shaped toothed green leaves that emit a pungent garlic odour especially when crushed. Flowers are white from 3-5mm in diameter and born in terminal clusters. Seed capsules are long and slender from 20-70mm in length

Characteristics

  • Foliage Evergreen

  • Habit Bushy

  • Fragrance Foliage

  • 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 Shade

  • Partial Shade

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

  • Exposure Sheltered or Exposed

Soil

  • Sand

    Sand

  • Chalk

    Chalk

  • Loam

    Loam

  • MoistureMoist but well-drained

  • SoilSand, Chalk, Loam

  • pHAlkaline, Neutral, Acid

Size

  • Ultimate height 0.5-1 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 1-2 years

How to grow

Cultivation Prefers a rich damp alluvial soil, thriving in damp shady places where few other herbs will grow. A good woodland-edge and hedgerow plant, the plant emits a strong smell of garlic which is especially pronounced if the leaves are bruised. This species is an important food source for the orange-tip and green-veined-white butterflies

Propagation Propagate by seed as soon as ripe. If sowing in situ, it is best to sow in autumn as it requires a long period of chilling to break dormancy

Suggested planting locations and garden types Wildlife Gardens

How to care

Pruning No pruning required

Pests Susceptible to caterpillar damage

Diseases Generally trouble free

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