Plant growth regulators play a crucial role in various aspects of plant propagation and development. Synthetic auxins, such as IBA, are widely used to promote root development in stem cuttings. This study was conducted to evaluate the effects of different concentrations of IBA (0, 500, 1000, 1500, and 2000 ppm) on the successful cuttings percentage, days for leaf sprouting as well as shooting and rooting characteristics. Soaking stem cutting with IBA led to decreasing days for leaf sprouting and increasing success cutting percentage, plant height, stem diameter, number of branches and leaves, root length as well as fresh and dry weights of shoot and root. All those characteristics significantly increased with increasing IBA levels, and the highest values have been observed when cutting treated with IBA at 2000 ppm. The results of this study recommend soaking bougainvillea stem cutting with IBA at 2000 ppm for two hours to ensure the success of rooting and to obtain greater vegetative and root system growth in the long term for the plant.