I agree with Wally,that if you want the same plant that you have,cuttings are the best way,or a friend has one you like.but if you want to cross polinate and come up with a new one then seeds.I dont agree that its the best way to produce more plants.I can plant thousands of seed in the winter and by spring have thousands of plants here is how I do cuttings of hibiscus.Both ways have their good merits.especially since some hibiscus and even the rose of sharons are sterile. Here is a link that might be useful: how I do hibiscus cuttings

Hibiscus Syriacus "Rose of Sharon" are really tough plants and can take a lot of abuse but now is not a good time for planting them. They will almost certainly suffer some transplant shock which is normal. Full sun and the high temps being experienced across the country could do more harm than good. I've always had excellent results transplanting in early spring or fall. That gives the rootball time to settle in before weather extremes become a factor. Rosie

just posting so this will move on down....

Hi- I know it would seem logical to post that question in this forum, but Rose of Sharon is actually not a member of the rose family- it's a kind of hibiscus. If I recall correctly, that family roots fairly easily from cuttings. But you might want to try one of the other forums to find someone with more direct experience.