You need to start out with 2 or 3 small ones 4.5 inch containers if you can find them and then patiently wrap the green stems around each other. In most cases it will take two years in the south to get what you see sold as a braided tree. You also need to prune all but the 2 or 3 leaders off throughout this time period.
They are tropical hibiscus so you will need to bring them inside to a sunny area of the home for the below 50 degree fall thru early spring time period.
Too much work and time for me personally but good luck in your quest and Happy Growing David

Thank you!!! Do you know if a rose of sharon can be trained into a tree form? It would be more hardy and still be pretty.

Yes, just follow same idea as already expressed.
Good Luck and Happy Growing David

Thank you so much David! To top it all off, I received rose of sharon seeds for free the other day!!! I can't beat that!