I have certain combinations that I like, and others that I actively dislike and try to avoid. One can plan color location when one is starting a new Iris bed -- but as time goes by, and you lose some or enlarge a bed -- it mostly does come down to an available space with eye toward avoiding unpleasant combinations, or duplications of color like Arlyn said. They're all beautiful, after all, and I tend to see them individually regardless of where they're planted.
