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BogsHerbaceous Perennial

Iris pseudacorus
  • RHS Plants for pollinators

yellow flag

I. pseudacorus is a vigorous herbaceous perennial forming extensive colonies to 1.5m in height, with bright yellow flowers up to 10cm in width, the falls with brown veining in the centre, in mid and late summer

Other common names
yellow iris
daggers
see moreflagon
Jacob's sword
water flag
water skegs
yellow fleur-de-lis

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Size
Ultimate height
1–1.5 metres
Time to ultimate height
2–5 years
Ultimate spread
1–1.5 metres
Growing conditions
Clay
Loam
Moisture
Poorly–drained
pH
Acid
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Yellow Green
Autumn
Winter
Position
  • Full sun
  • Partial shade
Aspect

South–facing or East–facing

Exposure
Exposed or Sheltered
Hardiness
H7
Botanical details
Family
Iridaceae
Native to the UK
Yes
Foliage
Deciduous
Habit
Suckering
Potentially harmful
Ingestion may cause severe discomfort. Wear gloves and wash hands after handling
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

Correct

Plant range
Europe Africa Asia

How to grow

Cultivation

Grow in wet, deep, acid, humus-rich soil in full sun or partial shade. It thrives at the margins of large ponds or streams; vigorous so site with care

Propagation

Propagate by division from midsummer to early autumn, plant immediately in flowering positions

Suggested planting locations and garden types
  • Coastal
  • Cottage and informal garden
  • City and courtyard gardens
  • 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 (Botrytis)

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