I am not as hot and dry as you are, but I put all rhizomes into the ground after a short soak of the roots in water. Then I water those newbies about 3 times a week for several weeks to encourage root development. No storage and no pots for me. I'd let the pots get too dry and forget about the stored ones.
Irises don't like a high nitrogen fertilizer so use one with a low first number, and only sparingly, usually in the spring only [and after first bloom for rebloomers]. If clay type soil plant a little high in a hill to encourage drainage.
Good luck with them.
