Iris pseudacorus

RHS Plant Profile

yellow iris

Other common names

daggers, flagon, Jacob's sword, water flag, water skegs, yellow flag, yellow fleur-de-lis, iris felen

Bogs Herbaceous Perennial

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A vigorous herbaceous perennial, forming extensive colonies to 1.5m in height, with waxy grey-green leaves and bright yellow flowers up to 10cm in width, the falls with brown veining in the centre, in mid and late summer

Position

Full sun, Partial shade

Soil Types

Clay, Loam

Max Height

1-1.5 metres

Max Spread

1-1.5 metres

Size

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

Growing Conditions

Clay Loam

Moisture: Poorly–drained
pH: Acid

Position

Full sun Partial shade

Aspect: South–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: Yes
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: 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; has the potential to become a nuisance if not managed well, so plant with care. See aquatic weeds for more information

Propagation

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

Suggested planting locations and garden types

Cottage and informal garden
Wildflower meadow
Wildlife gardens

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)