I know that Autumn Splendor can get to 3.5' tall here. My Dr. John isn't very big after 1 season, and is still in a pot. You don't have to plant them in pots first unless you want to. I've not been able to see much difference unless the plants are on the smaller side when you receive them.

Last September one of the members of my local society gave a presentation about minis and mini floras. She had a specimen of one mini flora and I was shocked when I saw it. This rose was bigger than some of my floribundas. :-( I wish I could remember the name of that rose. I'll have to ask her when I get back up north. I guess minifloras don't do it for me....