Plant Low-Growing Roof Iris for Its Charming Spring Flowers
Roof iris is a shorter iris plant with appealing spring flowers and great adaptability in the garden
Roof iris (Iris tectorum) offers the beauty of classic garden irises on a more compact plant that reaches just over a foot tall. This iris is also adaptable to varying moisture and light levels. Once established, it tolerates drought. It also resists deer.
Common name: Roof iris, wall iris, Japanese roof iris
Botanical name: Iris tectorum
Origin: Central to southwest China, Myanmar. This iris earned its colloquial and botanical names (the Latin tectorum means "roofs") when an 1860s plant explorer observed it growing atop thatched roofs in Japan. This placement reportedly began when an emperor ruled that land was to be used for growing food crops, not flowers.
Flowers: The species features 4- to 6-inch-wide, bright purple flowers in the typical iris shape, but more relaxed. There are varieties with lighter purple or white flowers. Bloom time is spring.
Foliage: Held in fans, the individual leaves are sword shaped and bright green. The foliage becomes somewhat outward spreading, compared to stiffly upright leaves of other garden irises. Evergreen in warmer climates.
Size and habit: Roof iris grows 12 to 18 inches tall and wide. It spreads by rhizomes and can quickly fill up available space. It is not considered invasive and can easily be contained by digging out any unwanted rhizomes, which remain quite shallow.
Related: How to Divide Irises in Summer
Growing roof iris
Exposure: Full sun to part shade
How to grow it: Plant the rhizomes just one to two inches deep. Roof iris prefers rich, moist soil with good drainage, but it is adaptable to challenging conditions, including both wet soil and drier spots. It grows well in both full sun and partial shade. Darkened leaves may indicate a viral infection, and those plants should be removed. USDA Zones 4–9, but provide a protective winter mulch and place in a south-facing location in Zone 4.
