These were 4-5 ft tall when I got the seeds off of them. I think it depends upon how much water they get (down here plants tend to get tall and leggy if they don't get enough rain on a regular basis). The first year I had them I didn't get seed pods, and they did not get as tall either. You can cut them back pretty much any time they get too tall and they will be fine. I am also pretty sure they grow in planting zones 5-9.
I noticed youo live in Ocala ... I lived there about 42 years ago at Half Moon Lake. :) (In a mobile home.) I fanned you too ... :) I usually have seeds listed, but I'm between auctions right now. :)