I'm in the deep south and mine are blooming away right now. I do have them planted under the canopy of huge oaks, so that may be why they are so green and lush. But I see them blooming all around my neighborhood.

Betty

Mine are not blooming as well as they have in previous years. Last year the blooms were large. This year, they seem stunted. Why? I have no earthly idea. However, the foliage is green and healthy looking. We are little south of Charleston, and the conditions are about the same. Mine are in semi-shade.

I have never seen anyone keep them pruned, but I passed by a yard the other day where there was a white one was just covered with blooms. By the shape, I guess that it had been carefully pruned. It was thick and lush. It made me think that maybe a good pruning might be a great idea. But when would you do it?
PB

I have a double peachy pink ROS that loves it here, outside of Beaufort. A deep pink double is barely making it, always looks puny. The singles have never done well for me.

My first closeup experience with Rose of Sharon was when we lived in Dothan, AL several years ago. The ones in our yard were a few years old and absolutely gorgeous. I've had mixed results here in coastal Georgia, but I think it's probably the individual plant rather than the climate. For some reason the doubles seem easier to grow than those beautiful singles.

A tad of fertilizer might make a difference, it helped this one.

They do better in the Piedmont and points further north...and i am not sure if it is the soil, or our lack of cold and sustained cool weather. In 8b or better, you can grow most cultivars of tropical hibiscus as perennials, with the red variety being hardier than others and some winters mainting all of its branches and leaves....most years they are just defoliated ( like a ROS would be anyway) and you have a greater color palette to choose from.

I have a single white that I rooted from a cutting I got from my neighbor. It's pretty right now. Want me to root a cutting for you?

I had the exact same problem with mine. When I bought it from the nursery it was gorgeous. It was a deep green & covered with beautiful white blooms. For years it got to be a pale green, very spindly, & hardly ever bloomed.
I then started fertilizing every week with a 20-20-20 solution & also watering a lot. It really started thriving. I bet this will solve your problem also.
I think different varieties of this plant must need more care than others. The purple variety that I grew when I lived in Lubbock, TX. thrived with no fertiilizer & very little water. The one I have now has to be babied.