Iris unguicularis 'Walter Butt'

RHS Plant Profile

Algerian iris 'Walter Butt'

John Fielding

Synonyms

Iris 'Walter Butt'

Herbaceous Perennial

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A rhizomatous, evergreen perennial to 30cm, with long, narrow, dark green foliage. Very fragrant, pale lavender flowers, with an orange streak on the falls, appear from late autumn into winter

Position

Full sun

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.1-0.5 metres

Max Spread

0.1-0.5 metres

Size

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

Growing Conditions

Chalk Clay Loam Sand

Moisture: Well–drained
pH: Alkaline or Neutral

Position

Full sun

Aspect: South–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): H5

Colour & Scent

Fragrance Flower

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Iridaceae
Native to GB/Ireland: No
Foliage: Evergreen
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

How to Grow

Cultivation

Grow in well-drained or sharply drained, neutral or slightly alkaline soil. Ideal at the base of a sunny wall

Propagation

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

Suggested planting locations and garden types

City and courtyard gardens
Coastal
Cottage and informal garden
Patio and container plants
Banks and slopes
Cut flowers
Wall side borders
Flower borders and beds

Pruning

Cut back after flowering

Pests

May be susceptible to slugs and snails

Diseases

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