Iris 'Clarke Cosgrove' (Spuria)

RHS Plant Profile
iris 'Clarke Cosgrove'

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Bulbs

Grows to 1.5m, with long, glaucous green leaves and stems bearing up to 4 flowers, with standards light violet-blue, veined yellow at the base, the falls light violet-blue with yellow veining and a yellow haft

Position

Full sun, Partial shade

Soil Types

Clay, Loam, Sand

Max Height

1-1.5 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity
2–5 years
Max Spread
0.1-0.5 metres
Max Height
1-1.5 metres

Growing Conditions

Clay Loam Sand
Moisture
Moist but well–drained or Well–drained
pH
Acid or Neutral

Position

Full sun Partial shade
Aspect
South–facing or East–facing or West–facing
Exposure
Exposed or Sheltered
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

Botanical Details

Family
Iridaceae
Native to GB/Ireland
No
Foliage
Deciduous
Habit
Clump forming
Potentially harmful
Harmful if eaten. Wear gloves and other protective equipment when handling. Pets: Harmful if eaten. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
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
Name Status
Accepted
Horticultural Group

Horticultural Classification Codes

Horticultural Classification Codes are often given to genera which have a large number of species or cultivars. They are used to categorise cultivated plants based on specific, shared characteristics such as shape, colour, size or flowering time, and can be displayed as letters or numbers

For example:
Dahlia ‘Sunset Kate (Sin) = Single flower
Rosa ‘Marigold’ (HT) = Hybrid Tea

Spuria section irises are rhizomatous perennials with several beardless flowers up to 15cm across, in late spring or early summer

How to Grow

Cultivation

Grow in well-drained, fertile, neutral to slightly acid loam in full sun

Propagation

Propagate by division of rhizomes from midsummer to early autumn

Suggested planting locations and garden types

  • City and courtyard gardens
  • Coastal
  • Cottage and informal garden
  • Flower borders and beds
  • Wall side borders

Pruning

Remove any dying foliage in autumn, old flower stems can be cut down after flowering

Pests

May be susceptible to slugs, snails and thrips

Diseases

May be susceptible to aphid-borne viruses, bacterial soft rot and grey moulds; see Iris diseases