Biomodification of coal fly ash with water hyacinth (Eichornia) with respect to improvement in physicochemical properties was done for the cultivation of Calendula. Few pot experiments were conducted to study the effect of levels of biomodified coal fly ash (CFA) on physicochemical properties of soil on the yield parameters of Calendula. Physicochemical studies have been carried out for different composts obtained by successive replacement of biomodified CFA for soil/earth in constituents of original and reference compost. In present studies CFA and water hyacinth of local origin were used. Increase in rate of growth and improvement in quality of produce was observed with the increase in percentage of biomodified CFA up to 80% with lesser use of fertilizers and irrigation water.