The first set of photos were taken on 15 Oct 2012 and these two Hibiscus were displaying the symptoms of severe nutrient deficiency. They were in a very bad state and the younger and older leaves were all showing interveinal chlorosis and possessed yellowish leaves. There were barely any flowers.
Now, after months of treatment to incorporate straight fertilizers in Nitrogen, chelated Iron and Magnesium as well as organic fertilizers to the soil, the two Hibiscus have recovered significantly and are now spotting lots of flowers, at least when compared to before.
Nutrient deficiencies in Iron are commonly seen in acid loving plants such as Wrightia religiosa and Gardenia etc.