Japanese water iris tend to be some of the most beautiful examples of the species. They tend to be quite large, 5-6 inches across, coming out in summer into fall. 'Yuzen' petals feature a bright rim of purple over creamy white, like fabric dipped in rich dye, as the name implies.
These plants would rather have heavy boggy wet soil rather than the typically well-drained soil that most plants prefer. Plant these iris near--or even in--water for best results. If you want them planted in containers, use heavy clay soil mixed with some sand. After a few years, you may want to dig up the rhizomes and separate them. When the rhizomes are crowded, the flowering becomes less. Hardy to zone 4.