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Herbaceous Perennial

Iris tectorum

Japanese roof iris

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

Other common names
roof iris
wall flag
see morewall iris
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Size
Ultimate height
0.5–1 metres
Time to ultimate height
2–5 years
Ultimate spread
0.1–0.5 metres
Growing conditions
Loam
Sand
Moisture
Well–drained
pH
Neutral, Acid
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Purple White Green
Autumn
Winter
Position
  • Full sun
  • Partial shade
Aspect

South–facing or East–facing or West–facing

Exposure
Sheltered
Hardiness
H6
Botanical details
Family
Iridaceae
Native to the UK
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

Get involved

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