Fluorescent Poly (methylmethacrylate) films embedded with a commercial coumarin dyestuff (MACROLEX Fluorescent Red G) were prepared by flow-spin coating technique. The absorption and emission spectra were recorded in order to determine the dye concentrations corresponding to the maximum fluorescence intensity and red shift. The emission band was optimized to match to the absorption band of chlorophylls (650-680 nm), which is the most important wavelength band for the photosynthesis process in plants. These films showed a remarkable stability against both photo and thermal degradation, pointing to their excellent weathering durability for using as photoselective films in greenhouse applications.