Iris tectorum
Common Name: roof iris 
Type: Herbaceous perennial
Family: Iridaceae
Native Range: Central and southwestern China, Myanmar
Zone: 4 to 9
Height: 1.00 to 1.50 feet
Spread: 1.00 to 1.50 feet
Bloom Time: May
Bloom Description: Deep lilac-blue purple with white crest
Sun: Full sun to part shade
Water: Medium
Maintenance: Low
Suggested Use: Naturalize
Flower: Showy, Good Cut
Tolerate: Deer, Drought


Grow in organically rich, medium moisture, well-drained soil in full sun to part shade. Prefers sheltered sunny locations, as near a south or west facing wall. Plant rhizomes only about 1-2" below the soil. Rhizomes tend to push out of the ground and will benefit from fall and spring mulches.

Noteworthy Characteristics

Iris tectorum is a 15" tall species of the crested iris group featuring large, 6" across, beardless, bright lilac-purple flowers with falls which are crested white. Foliage is arranged in fans of narrow, lance-shaped, ribbed, glossy, upright leaves that can become somewhat floppy. Can spread rapidly in the garden. Commonly called roof iris because it has in the past been grown on thatched roofs in both Japan and China.

Genus named for the Greek goddess of the rainbow.

Specific epithet means of the roofs of houses.


Susceptible to a virus which discolors the leaves badly. Remove and destroy infected plants. Seed will be virus-free and can be collected for future planting. Also subject to slugs.


Because of its preference for sheltered, sunny areas, this iris can solve a planting problem in areas of the garden where there is limited air circulation. It also may be effective when planted in the rock garden or in large drifts at the front of the perennial border. The ribbed leaves add texture to the garden.