Greetings! I have a number of Rose-of-Sharon in my yard and, while pretty, most of them are nuisance shrubs, reseeding with abandon (I have learned to religiously deadhead them every fall before they set seed). I am looking to fill in gaps in a hedgerow which already has some hibiscus in it (the deer don't like them!) I have read about the triploid hibiscus with the goddess names which are seedless, but find them hard to come by (and as I recall expensive?) I do however have a very pretty double red Rose-of-Sharon (came with the house) which I like a lot and which has never once set a seed pod in 15 years. There seems to be somewhat inconsistent information on the Internet regarding whether double ones set seed or not. Might anyone have any additional information or recommendations and sources for me? I have about 20 feet of hedge row to fill in and would like bushes which will get 6-8 foot tall. My current thinking is to intersperse these with non-suckering lilacs (the latter being questions for another forum ;-)

Thanks!