• 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 korolkowii

© RHS

  • 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

  • Details I. korolkowii is a rhizomatous herbaceous perennial, 40-60cm high, with narrow, glaucous leaves and creamy-white flowers with maroon-brown veins on both standards and falls, maroon-brown blotches on the falls, and inconspicuous yellow beards, in early summer

  • Plant range C Asia

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)

    H4

Colour

Sunlight

  • Full Sun

  • Aspect South-facing or West-facing

  • Exposure Sheltered

Soil

  • Chalk

    Chalk

  • Sand

    Sand

  • Loam

    Loam

  • MoistureWell-drained

  • SoilChalk, Sand, Loam

  • pHNeutral, Alkaline, Acid

Size

  • Ultimate height 0.5-1 metres

  • Ultimate spread 0.1-0.5 metres

  • Time to ultimate height 2-5 years

How to grow

Cultivation Grow in very well-drained soil, in full sun, and with the top surfaces of the rhizomes exposed so that they get baked in summer sun, which encourages flowering; best grown in a bulb frame in containers using gritty, free-draining compost, and kept dry during late summer and winter; may be grown outside in a well-drained sunny site on a bank or in front of a sunny wall, if given protection from heavy winter rain

Propagation Propagate by seed, or by division of rhizomes after flowering; for more advice, see dividing irises

Suggested planting locations and garden types Wall-side Borders Flower borders and beds Drought Resistant Gravel Garden Cottage & Informal Garden City & Courtyard Gardens

How to care

Pruning Remove old flower stems after flowering, and any dying foliage

Pests May be affected by iris sawfly, aphids, leaf miners, slugs, snails, and wireworms

Diseases May be affected by virus diseases, iris rhizome rot, iris leaf spot, scorch, and a rust; for more advice see iris diseases

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