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Herbaceous Perennial

Iris douglasiana

Douglas iris

An evergreen perennial to 70cm tall, with narrow, dark green leaves and usually branched stems bearing purple or lavender-blue flowers up to 10cm wide in late spring, the falls often with a white basal patch

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Ultimate height

0.5–1 metres

Time to ultimate height

2–5 years

Ultimate spread

0.1–0.5 metres

Clay

Loam

Sand

Moisture

Moist but well–drained, Well–drained

pH

Acid, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun
Partial shade

Aspect

South–facing or North–facing or West–facing or East–facing

Exposure

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)

Botanical details

Family: Iridaceae
Native to GB / Ireland: No
Foliage: Evergreen
Habit: Bushy
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: North W America

How to grow

Cultivation

The most easily grown of the Pacific Coast Iris tolerating slightly drier and more alkaline soils

Propagation

Propagate by seed or division in spring

Suggested planting locations and garden types

Coastal
City and courtyard gardens
Cottage and informal garden
Flower borders and beds

Pruning

Remove dead foliage, 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

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