• 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

Iris 'Tropic Night' (Sib)

Siberian iris 'Tropic Night'

  • Other common names Siberian iris 'Tropic Night'

  • Synonyms Iris sibirica 'Tropic Night'

  • Family Iridaceae

  • Genus Iris may be rhizomatous or bulbous perennials, with narrow leaves and erect stems bearing flowers with 3 large spreading or pendent fall petals, alternating with 3 erect, often smaller, standard petals, in late winter, spring or early summer

  • Horticultural Group Sibirica irises are rhizomatous perennials, to 1.2m tall, with narrow leaves and erect stems bearing up to 5 beardless flowers 6-7cm wide in early summer. Form and colour vary considerably among cultivars

  • Details 'Tropic Night' has delicate purple-blue flowers with white and yellow markings that are borne above clumps of linear foliage for several weeks in early summer

Characteristics

  • Foliage Deciduous

  • Habit Clump-forming

  • Toxicity Ingestion may cause severe discomfort

  • 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)

    H7

Colour

Sunlight

  • Full Sun

  • Partial Shade

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

  • Exposure Exposed or Sheltered

Soil

  • Chalk

    Chalk

  • Clay

    Clay

  • Sand

    Sand

  • Loam

    Loam

  • MoistureMoist but well-drained

  • SoilChalk, Clay, Sand, Loam

  • pHNeutral, Acid

Size

  • Ultimate height 1-1.5 metres

  • Ultimate spread 0.5-1 metres

  • Time to ultimate height 1-2 years

How to grow

Cultivation This cultivar is suited for cultivation in both herbaceous borders and informal pond-side settings. Grow in moist but well-drained neutral to slightly acid loam in full sun or partial shade

Propagation Divide clumps in early spring or autumn

Suggested planting locations and garden types Flower borders and beds Cut Flowers Low Maintenance Cottage & Informal Garden

How to care

Pruning Deadhead after flowering. Cut back foliage in autumn

Pests Slugs and snails may be a problem

Diseases May be affected by aphid borne virus diseases

Advertise here

Did you find the information you were looking for?

RHS members can get exclusive individual advice from the RHS Gardening Advice team.

Join the RHS now