In this study, the effect of different rooting mediums (peat moss, peat + sand, peat + loam) and IBA (indole-3-butyric acid) concentration was investigated on hardwood cuttings taken from Bougainvillea glabra, Bougainvillea spectabilis, and Bougainvillea x buttiana species. The cuttings were treated with 0, 1000, 2000 and 3000 mg/l IBA. Statistical evaluation was performed according to a randomized block experimental design with three factors and three repetitions. The results showed that Bougainvillea x buttiana cuttings had the highest number of roots, root fresh weight, longest shoot length, and shoot fresh weight. Cuttings grown in 100% peat medium had the highest rooting percentage, root number, root dry weight, leaf number, and shoot fresh weight. Regarding IBA concentrations, the cuttings treated with 3000 ppm IBA had the highest number of roots, root length, and root fresh weight. Furthermore, in all of the Bougainvillea species, the highest rooting percentage and leaf number were observed in cuttings treated with 2000 ppm IBA. Notably, Bougainvillea x buttiana cuttings treated with 1000 ppm IBA dose and planted in peat medium provided the longest shoot length, highest shoot fresh weight, and shoot dry weight. In conclusion, the findings show that the growing medium has a statistically significant effect on the rooting and root quality of cuttings and that it would be useful to investigate various rooting hormones, dasages and rooting media to increase rooting and shoot development. Considering growing medium plays a crucial role in plant growth, it can be stated that further improvements in rooting and growth can be realized via utilizing the enhanced physical and chemical properties of peat-based mixtures.