Gamma radiation is an effective mutational breeding method for improving various growth and floral characteristics of ornamental plants. This Experiment was undertaken with an objective to investigate the effect of gamma irradiation on the growth and floral characteristics of G. pulchella plants during the third generation (M₃). Irradiation treatments were performed on the seeds in the first generation only, Gamma-1 type cobalt60 was used to expose seed plants to different dosages such as 0, 10, 20, 30, 40, 50 and 60Gy. The results indicated that control plants gave the highest values of seed germination; meanwhile, the lowest value was recorded with 60 Gy. The tallest plants, greatest leaves number, biggest stems, longest roots, early flowering, and largest flowers number were achieved with the doses of 10, 20, and 40 Gy over the control. In contrast, with increasing the radiation level to 50 and 60 Gy had a negative effect, and decreased these characters to the lowest values, but increased the number of days elapsed to flowering. All the investigated characters exhibited significant positive correlations, except for number of days from planting to flowering, which was significantly negatively correlated with all characters. All flowering characters correlated with each other in a medium to high significant correlation. Using gamma increased relative water content, but decreased electrolyte leakage compared to the control. All gamma doses decreased membrane stability percentage; in except for the smallest dose (10 Gy). Using 10 and 20 Gy gave the highest values of number of disc flowers rows, diameter of flowering bud, and receptacle.