Iris 'Black Swan' (TB)

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iris 'Black Swan'

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iris 'Black Swan' RHS
iris 'Black Swan' RHS
Herbaceous Perennial
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A herbaceous perennial, to around 90cm tall, with narrow, pointed, grey-green leaves. The flowers have deep purple standards and very deep purple-black falls; beards are pale purple with orange-brown tips

Position

Full sun

Soil Types

Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

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

Growing Conditions

Loam Sand
Moisture
Well–drained
pH
Acid or Neutral

Position

Full sun
Aspect
South–facing or West–facing or East–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

Colour & Scent

Season Stem Flower Foliage Fruit
Spring
Summer
Autumn
Winter

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

Tall Bearded irises are herbaceous rhizomatous perennials to 70cm or more, with flowers 10-20cm across, bearded on the falls, in late spring and early summer

How to Grow

Cultivation

Grow in well-drained, fertile, neutral to slightly acidic soil in full sun. Do not cover the rhizomes with mulch, or allow other plants to shade them; sun on the rhizomes encourages flowering. Give a high potash feed in spring and divide every three to four years. See also bearded iris cultivation

Propagation

Propagate by division of rhizomes from midsummer to early autumn; see dividing irises

Suggested planting locations and garden types

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

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