PlantFiles: Japanese Root Iris, Roof Iris, Wall Iris
Iris tectorum

Planted our very first green, as in vegetated, roof over our sunroom back in the fall of 2008. Planted the usual sedums , but also planted a swath of tectorum, Roof Irises, including a few Iris tectorum 'Jimmy Stewart,' a white flowered cultivar. A 'Jimmy Stewart' iris was the very first to bloom that very first spring in 2009, followed by many more blooms. The irises have continued to thrive and we divided the clumps in the fall of 2011.

The sedums are doing fine but the Irises create a stunning green roof garden, blooming and spreading, even with just 5" of growing material. If we can have a successful green roof, anyone can. Highly recommend including this iris in your green roof planting.

I have had great success growing " roof iris", I grew it from seed ( from
Gardensnorth ) and I've moved it twice, the first place I had it was far too hot and dry, but now it's in partial shade and the foliage and flowers are wonderful.
Mine are the blue, and one day soon I'd love to get a couple of the white, or the seeds for it. The foliage is beautiful, and I'd enjoy this plant even if it never flowered. ( I'm in zone 3 - 3b?? and this iris takes all of our weather, heat and cold, in it's stride ) I'm in central-south Alberta, Canada.

My favorite pass-along plant. Grows in sun or shade. Only care needed is to cut back old foliage in spring -- here in zone 5 the foliage persists thru the winter, unlike standard iris, which dies back and sprouts cleanly in spring. My variety is white and its blossoms remind me of the flying nun. Foliage is similar to standard iris but more graceful. Love it!

They will bloom in the shade or sun, but the only iris I know of that blooms in the shade.

PLANT THRIVES IN INDIANA CLIMATE. NEEDS LITTLE OR NO FEEDING. SUN OR PARTIAL SHADE WORK FINE.
SEEDS PRODUCE SECOND YEAR BLOOM IN SLIGHT VARIATIONS OF SHADES OF LAVENDER WITH OCCASIONAL WHITE. PODS PRODUCE LARGE QUANTITIES OF SEED.
NICE PLANT FOR THE NATURALIZED ROCK GARDEN. FOLIAGE STAYS NICE AND GREEN FOR THE SUMMER BUT TENDS TO BE A LITTLE FLOPPIER THAN MANY OF THE SPECIES IRIS.

The Japanese Roof Iris does very well in coastal South Carolina and provides an interesting "topic" plant. Mine was planted in 1990 and has thrived ever since with very little care and only 2 fertilizations during that period of time.

Roof Iris or Root Iris? Or is it a Wall Iris?

It IS grown on thatch roofs in Japan, hence its most common vernacular name. Some sources suggest that when space became too precious for anything but food crops, Japanese women - who used the powdered rhizomes as a face powder - began growing Iris tectorum on their thatch roofs. Other legends indicate it was used to ward off evil spirits; or perhaps it was for purely pragmatic reasons (to help hold the thatch together.)

"Root Iris" is less-often used, and possibly the result of a misinterpretation of "Roof".

"Wall Iris" is its third common name, and it's suggested for planting near a wall (it will take more shade than many other Iris species.)

No matter what you call it, the pleated leaves and pretty blooms make it well-worth growing in your garden (or thatch roof!)