Minerals required for best quailty of blue flowers

A number of years ago when I was growing hydrangeas we used aluminum and other minerals to lower the pH which worked great for turning hydrangea flowers blue. For fun I tried the same technique with hibiscus and did not see any result. However, that was a quick and not very extensive test of the idea and since then a few people have reported getting some results by feeding hibiscus various substances. I'm not convinced the effect is very significant or long lasting but am open to learning more if anyone has some results to share. Generally speaking, potassium nitrate is the substance that many people have used to intensify all colors in hibiscus flowers as well as flower size. I don't have any scientific evidence of this but my own experiences using it do tend to confirm the flower stimulating effect of added potassium nitrate.

Sorry not to have more specifics about this interesting topic. I hope you and others will continue to research and experiment ways to increase the blue colors in hibiscus!

Charlie