Iris tectorum

RHS Plant Profile

Japanese roof iris

Other common names

roof iris, wall flag, wall iris

Herbaceous Perennial

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An upright perennial, to around 40cm high, with fans of sword-shaped, ribbed green leaves. Flowers are pale violet streaked with purple, or occasionally white, with strongly ruffled edges to both standards and falls

Position

Full sun, Partial shade

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: Neutral or Acid

Position

Full sun Partial shade

Aspect: South–facing or East–facing or West–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): H6

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: Correct
Plant Range: China

How to Grow

Cultivation

Grow in well-drained, fertile, neutral to slightly acid soil in full sun

Propagation

Propagate by division, see dividing iris for more detailed advice

Suggested planting locations and garden types

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

Pruning

Remove spent flower stems in summer, and any dying foliage in autumn

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