Roof Iris, Wall iris, Japanese Roof, White Root Iris
Iris tectorum
Family: Iridaceae
What it is like
Bloom Color: Purple. Main Bloom Time: Early summer, Late spring. Form: Upright or erect.
Iris tectorum is an evergreen Perennial growing to 0.3 m (1ft) by 0.5 m (1ft 8in) at a medium rate. See above for USDA hardiness. It is hardy to UK zone 6. It is in leaf all year, in flower from May to June. The species is hermaphrodite (has both male and female organs) and is pollinated by Insects. The plant is self-fertile. Suitable for: light (sandy) and medium (loamy) soils and prefers well-drained soil. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers dry or moist soil and can tolerate drought.
Height (m): 0.3
Where it is found
Grows wild on shady rocky slopes and in scrub, it is also found planted on thatched roofs in Japan. Forest margins, sunny banks, meadows, damp places, beside water to 3500m.
E. Asia - China, Japan.
Conservation Status:
Countries/locations it is found in
How it is used
Food
Rating: 1
Root - an edible starch is said to be extracted from it. Some caution is advised since there are reports that the plant might be poisonous. Perhaps the extracted starch is edible.
Root: includes bulbs, corms, tubers, rhizomes etc.
Medicine
Rating: 0
Other
Rating:
How it is grown
Landscape Uses:Border, Container, Massing, Seashore. Prefers a well-drained loam rich in leafmold with plenty of moisture in summer and an open sunny position. Requires a really well-drained soil that is dry rather than damp, and a hot sunny position. Prefers a lime-free soil but succeeds in most good soils and in partial shade. Succeeds in dry soils and, once established, is drought tolerant. Cultivated for its edible root in Japan. There are some named varieties, selected for their ornamental value. In China the plants are grown on the roofs of houses. Plants do not flower so freely in cultivation in Britain. In their native habitat they experience cold dry winters and warm wet summers. It is best to lift the plants in October, store them in sand in a cool frost free place over winter and replant in March. Members of this genus are rarely if ever troubled by browsing deer or rabbits. Special Features: All or parts of this plant are poisonous, Attractive flowers or blooms.
Propagating it: Seed - best sown as soon as it is ripe in a cold frame. Stored seed should be sown as early in the year as possible in a cold frame. Stored seed does not require cold conditions in order to stimulate germination. Prick out the seedlings into individual pots when they are large enough to handle and grow them on in the greenhouse or cold frame for their first year. Plant out into their permanent positions in late spring or early summer. Division, best done in July/August after flowering. Very easy, larger clumps can be replanted direct into their permanent positions, though it is best to pot up smaller clumps and grow them on in a cold frame until they are rooting well. Plant them out in the spring.
Best place to grow: Cultivated Beds; East Wall. In. South Wall. In. West Wall. In.
Habit: Perennial
Hardiness: 5-9
Growth: Medium
Soil: Light (sandy), medium
Shade: Semi-shade, no shade
Moisture: Dry, moist
Things to keep in mind
Many plants in this genus are thought to be poisonous if ingested, so caution is advised. The roots are especially likely to be toxic. Plants can cause skin irritations and allergies in some people.