I dried a bouquet of roses like that once and I just hung them off a hook in the dining room! It would have been in the fall, not a humid summer. They looked great. I admit I don't know anything else about this topic though, I was just so happy to have gotten a bouquet of roses I wanted to keep them forever. So I gave it a try. They are long gone now. LOL I got tired of them!
Hopefully someone else will have a more, detailed, fact-based answer for you.