Nicole, your hib could have mites, or lack of iron..If you suspect pests, look over the entire plant and check for webbing. Mites weave fine webbing similiar to the house spider but finer.
BTW, there are other bugs hibs can get like mealy. White cottony patches. Inspect the plant and look for anything that shouldn't be there.
Over and Under-watering causes leaves to yellow too..You want the soil to dry between waterings; Hibs do not like wet feet.
If veins are a deep green and leaf is yellow it could be a mineral defincincy. If this is the case, add iron.
Yes, Rose of Sharon is in the Hib family..If given full sun it shouldn't weep. A warning about ROS..I don't know if it's seed or cuttings, but I've got them growing everywhere..LOL. When this happens pluck at an early age..or they'll take over and they're really hard to lift.
I don't envy you right now..digging up hibs..they make look bad at first, but should do fine after time. You'll have to dig deep to get all the roots though..Toni

I have the same yellow leaf problem. Everyone elses bushes are blooming. Last winter I really watered it (That may be part of the problem this year). The veins are dark green but the leaf is yellowish. Where can I get Iron and how much do you use.. Last week, a nursery fellow said put on sulpher.. He gave me a cup or so and I scratched it into the soil under the bush.. Thanks in advance, Bill

Bill, if the veins on your hib leaves are more pronounced, than it definatly sounds like an iron defincency..You can use either Iron sulfate or Iron Chelate. Both work fine.
Home Depot carries one or the other so you can start there..if you can't find it locally, then I'd start looking online.
www.homeharvest.com may sell it..I buy other items from them..they're fast and not overpriced like some nurseries.

As far as the dossage, it's best reading and following container directions..I don't want to give you an amount w/o knowing what you're going to use..Actually, some plants need iron 3 times a yr as a preventative..it's best not to wait until it's too late..do you know what I mean? Toni

thank you, i already cut it back, but do believe it was mites. I have 5 hibiscus and that one was the only one that looked pathetic. Thank you!