Welcome to the iris forum Rebekah! The only two TB's that I have had bloom truly blue is Absolute Treasure and Dodger Blue. I live in zone 7a. It is my understanding that there are a few more that bloom truly blue and I am growing a few waiting for my first blooms. As to being tall each cultivar has its hight listed in the database here. I find that irises with more substance, like ruffles, tend to be heavier and the stalks will need staking. A big bloom full of ruffles can be really heavy when rain soaked.
