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. 'Oriental Eyes' have full purple petals in sharp contrast with dots of yellow toward the center, as if a painted eye is winking at you.
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.