Possibly you haven't pruned.
To encourage the shrub to produce more flower buds, prune the plant in late winter before it breaks dormancy. For those of you troubled by deer eating your landscape shrubs, they would actually be doing you a favor by gnawing the branches of this one.
Now, growing this shrub does present a few challenges; over the years I have encountered many folks who, come early May, have declared their Rose of Sharon bush dead because there is no sign of greenery. Remember: Mother Nature often throws a curve to test our gardening patience, and the lateness of this shrub to break dormancy is a perfect example of her challenge to us.
Because it blooms so late in the growing season, it figures it can take most of the spring off, so remain patient. It will eventually leaf out in its own time. Go ahead, fertilize as you would any of your other shrubs and then just wait.
One of the most common Rose of Sharon health issues is "Flower Bud Drop." Your shrub may be in bud or full bloom and then the next day the buds/flowers have fallen off. To avoid this, the soil moisture must remain constant; it can't fluctuate excessively between dry and moist. This is why a rich, organic moisture retentive soil is recommende
Can I move a Rose of Sharon bush into a sunnier location now in Arkansas? It's about 12 ft. tall, wont' bloom
Quick fix for the bush---you need to trim off the seed pods and then it will bloom---if you leave them on--no blooms.
You need to use clippers don't just pull them off. I had oodles of them in NC and if no trim--no bloom.