Rebekah! Blues are very tricky. My truest blues are all shorter iris, especially dwarfs. Now if you want tall iris then please consider some by Tom Burseen. His yellow and white irises Abby And Me and Purr Form Mints are always the tallest in the garden. For dark Purple Black his Blackbird Landing is tall and has impressive large blooms. It has thick stalks but staking in high wind is still a good idea.