This study deals with the effect of glutamic acid and the reuse of chemically treated wastewater on the chemical constituents of Coreopsis tinctoria Nutt Plants in a batch-pot experiment. This chemical constituent includes the nutrient elements (N, P, K), micronutrient elements (Fe, Mn), sodium, as well as heavy metals (Cd, Cu, Zn). In this study different doses of glutamic acid were examined in combination with different types of treated wastewater to investigate the environmental stress on Coreopsis tinctoria Nutt Plants. The study was conducted during the two successive seasons of (2015/2016– 2016/2017) in the greenhouse of National Research Centre, Cairo, Egypt, aimed to study the response of Coreopsis tinctoria plants to glutamic acid application at four chemical concentrations (0, 50, 100 and 150 ppm) as well as the effect of treated wastewater as a source of irrigation. Besides, this investigation includes the impact on growth and flowering of Coreopsis tinctoria plants. The physical and chemical characteristics of the treated wastewaters were investigated and reused to determine the beneficial advantages as an additional water resource. It was concluded that Glutamic acid and irrigation with three types of treated wastewater effluents individually induced favorable changes in Coreopsis tinctoria Nutt plants in terms of chemical constituents, vegetation and flowering. Thus, the effluent of the chemically treated municipal wastewater can be reused safely without any side effect. Meanwhile, type of treatment has an important effect on the final chemical characteristics of the treated wastewater, particularly the nutrient elements and heavy metals. The reuse of treated wastewater is the most important challenge in the near future to increase the water budget in Egypt as the population escalating and the stringent need for more cultivated land. Consequently, the need for extra safe water resources should be supplied.