growing healthy hibiscus
Thanks for writing. Hibiscus will often abort their buds under periods of stress, such as if they get too dry, too hot, too wet, etc. So I'd start by checking the environment and ensuring the plants have an even supply of moisture.
Do you fertilize? Excess fertilizer can cause a similar issue on hibiscus because the fertilizer salts "burn" the roots.
---Justin, Senior Garden Editor, BHG.com