Fly ash generated from coal based thermal power plants creates environmental problems due to improper utilization and disposal. The present study was conducted to study the effects of various concentrations of FA (20, 40, 60, 80 and 100%) on the growth and photosynthetic activity of Oryza sativum (rice) and Zea mays (maize). Plant growth was mostly enhanced in the treatments with 20-40% fly ash, being optimal at 60%. From 80% onwards, the measured parameters tended to reduce. The most economic level of fly ash incorporation was 60%, which improved the growth of maize and rice. Hence fly ash can be utilized as a substrate or as a soil ameliorating material for the growth of plants, leading to the sustainable utilization of solid waste material.