How much sun is it getting (in hours)? Water (how much, how often, how long, with what)? Fertilizer (what kind, how much and how often)? What type is it as well? It may just be this infernal heat, but answering the above questions will give us a chance to see if it's something else.

It gets quite a bit of sun, but is next to a fense on the east, so it is shaded from about 3 or 4 on (except the top leaves which are taller than the fense).
I water it pretty deeply about once a week. I use a drip system.
I try to fertilize it, but not as often as I like. I've been using Miracle Grow--I was doing about once a week, but have been busy, so less often.
I don't know what type of ROS it is. I got it from my aunt. She had different colors, but I think it might be white hibiscus looking flowers (smaller than regular hibiscus). She lives by Tulsa and all the ROS bushes I saw up north were blooming about a month ago, but they are not as hot here.

Trees/shrubs that bloom such as Rose of Sharon and crepe myrtles, suffer from too much fertilizer. The result is lots of growth and no flowers. Benign neglect works for both.

Perhaps you are over-fertilizing it. Sometimes that can cause very good growth and lush foliage at the expense of flowering. I use a good slow release fertilizer when planting shrubs and if I fertilize after that, it's just a healthy sprinkling of the same fertilizer around the base of the plant every spring.
Last year in Spring, I planted a double purple Rose of Sharon in my front yard. It hasn't had any fertilizer since and it has doubled in size and is blooming very well right now.

I have always just let them fend for themselves and they always seem to do just fine. They can try to take over if you leave a few bare spots on the ground.

I agree with Texasredhead and AGibson ~ probably too much fertilizer, especially if it was heavy in nitrogen. Rose of Sharons ask very little in the way of care. They're everywhere for precisely that reason ~ they give such a nice show for little or no work. So ignore it and see what happens. It may take 'til next year for the residual ferts to go away so don't give up on it for a while yet.