Species Iris, Japanese Water Iris, Japanese Flag, Russian Iris

Japanese iris are hardy in Z4, some say Z3.

They are famously intolerant of alkaline soils. Optimal soil pH is 5.0-6.5. A...Read Morebove 6.5, they turn cholorotic (the leaves turn yellow).

They tolerate flooding when in bloom, but their requirement is for consistent moisture, not wet soils. They do well in well-drained soil and typical border conditions as long as it's never droughty.

Iris ensata blooms for a short period in midsummer. Some cultivars have flowers as big as dinner plates, and some are a true vivid blue -...Read More- absolutely stunning! It's probably one of the last irises to bloom (early July in New England.) This iris thrives in bogs but also does quite well in a sunny border with good, deep loam.

I had success with Japanese irises when I lived in Maine. Since then I have moved to Southern California, and have not attempted to grow them here.

I have to disagree with the culture sheet above which states that iris ensata tolerates "mildly alkaline" conditions. I've always understood that this plant is a true acid lover which can't tolerate lime in any form. For gardeners in alkaline-soil areas, it's generally recommended that plants be grown in pots (with a peaty potting mix) and left sitting in a saucer of water. However, be aware that your tap water might be alkaline too so watering with rainwater or distilled water would be preferable.

We place these in pots, cover with large rocks and pop them in our ponds and waterfalls. Reliable, startling early spring colour. I colle...Read Morected the seeds this year, and will be experimenting with them.