Hardiness: USDA Zone 5b: to -26.1 °C (-15 °F) USDA Zone 6a: to -23.3 °C (-10 °F) USDA Zone 6b: to -20.5 °C (-5 °F) USDA Zone 7a: to -17.7 °C (0 °F) USDA Zone 7b: to -14.9 °C (5 °F) USDA Zone 8a: to -12.2 °C (10 °F) USDA Zone 8b: to -9.4 °C (15 °F) USDA Zone 9a: to -6.6 °C (20 °F) USDA Zone 9b: to -3.8 °C (25 °F)
Sun Exposure: Full Sun Sun to Partial Shade
Danger: Parts of plant are poisonous if ingested Handling plant may cause skin irritation or allergic reaction
Bloom Color: Medium Blue Blue-Violet Violet/Lavender White/Near White
Bloom Time: Late Midseason (MLa)
Other details: Average Water Needs; Water regularly; do not overwater
Soil pH requirements: 6.1 to 6.5 (mildly acidic) 6.6 to 7.5 (neutral) 7.6 to 7.8 (mildly alkaline)
Patent Information: Non-patented
Propagation Methods: By dividing rhizomes, tubers, corms or bulbs (including offsets)
Seed Collecting: Allow pods to dry on plant; break open to collect seeds
On Apr 3, 2012, kdmclynn from Washington, DC wrote:
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.
On Sep 3, 2011, Mizfolia from Camrose Canada wrote:
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!
On Nov 25, 2004, rainbeau from Connersville, IN wrote:
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.
On Oct 12, 2003, docturf from Conway, SC (Zone 8b) wrote:
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.
On Oct 11, 2003, Terry from Murfreesboro, TN (Zone 7a) wrote:
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!)
This plant has been said to grow in the following regions:
Washington D.c., Montgomery, Alabama Tuskegee, Alabama Los Angeles, California Stockton, California Gainesville, Florida Fayetteville, Georgia Norcross, Georgia Calvert City, Kentucky Belleville, Michigan Lake Toxaway, North Carolina Raleigh, North Carolina Tulsa, Oklahoma Laflin, Pennsylvania New Hope, Pennsylvania Philadelphia, Pennsylvania Bluffton, South Carolina Conway, South Carolina Hartsville, South Carolina Houston, Texas Mechanicsville, Virginia Virginia Beach, Virginia Shorewood Hills, Wisconsin