• 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

Heuchera americana

American alum root

  • Other common names American alum root
    American sanicle

    rock geranium

    see more
  • Synonyms Heuchera glauca

  • Family Saxifragaceae

  • Genus Heuchera are more or less evergreen, clump-forming perennials with attractive, rounded, shallowly palmately lobed leaves and racemes or panicles of small, tubular flowers, often with colourful calyces

  • Details H. americana is a mound-forming, evergreen perennial with rosettes of lobed, oval to heart-shaped, glossy leaves. Young foliage is marbled and veined brown, maturing to deep green with copper-green shading. Sprays of tiny, browny-green flowers on tall, upright stems appear in early spring

  • Plant range E USA

Characteristics

  • Foliage Evergreen

  • 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)

    H6

Colour

Sunlight

  • Full Sun

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Clay

    Clay

  • Loam

    Loam

  • Sand

    Sand

  • MoistureMoist but well-drained

  • SoilClay, Loam, Sand

  • pHNeutral

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 Grow in a fertile, moist but well-drained, neutral soil in sun or partial shade. The woody rootstock tends to lift out of the ground so mulch annually or lift and replant

Propagation Propagate by seed sown in containers in autumn, or by division in autumn

Suggested planting locations and garden types Flower borders and beds Underplanting of Roses and Shrubs City & Courtyard Gardens Coastal Cottage & Informal Garden Patio & Container Plants Rock Garden

How to care

Pruning Remove faded flower spikes

Pests Prone to vine weevils and leaf and bud eelworm

Diseases May be affected by heuchera rust

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