• 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

Lewisia cotyledon

Siskiyou lewisia

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
Siskiyou lewisia

© � RHS 2002

  • Other common names Siskiyou lewisia

  • Genus Lewisia can be herbaceous or evergreen perennials forming rosettes of fleshy leaves, with panicles of open funnel-shaped flowers in a wide range of colours in spring and summer

  • Family Portulacaceae / Portulacaceae

  • Species L. cotyledon is a rosette-forming evergreen perennial with fleshy, strap-shaped leaves. Abundant, funnel-shaped purplish-pink, orange, yellow or white flowers 1.5-2.5cm in width are borne in open sprays on stems to 20cm

  • Plant range USA (California)

Characteristics

  • Foliage Evergreen

  • Habit Tufted

  • 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

    H4

Colour

Sunlight

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Chalk

    Loam

  • Chalk

    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 Grow in moderately fertile, neutral to acid, well-drained soil in full sun or light shade. Suitable for the alpine house, rock garden, or in the crevices of a retaining wall. Protect from winter wet

Propagation Propagate by seed or offsets

Suggested planting locations and garden types Gravel Garden Patio & Container Plants Rock Garden

How to care

Pruning No pruning required

Pests May be attacked by aphids, slugs and snails

Diseases May be subject to neck rots in wet conditions

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