I have a hibiscus that is healthy, but did not produce any blooms this summer.
Hibiscus Did Not Produce Any Blooms
Certified GKH Gardening Expert
It likely needs some more fertilizer, especially phosphorus which helps with blooming. Use a "bloom booster" fertilizer or add some bone meal to the soil to help add some phosphorus. You could also try giving it a teaspoon of Epsom salts dissolved in a quart of water.