Over centuries, the number of petals has been a critical criterion for evaluating rose flowers. Low temperatures are known to influence floral organogenesis significantly. This study investigated the effects of suboptimal temperatures on floral organogenesis in the spray-type cut rose ‘Pink Shine’. Six-month-old rooted cuttings were cultivated in environmentally controlled growth chambers at four temperature levels: 25/20℃ (optimal temperature, OT), 20/20℃, 20/15℃, and 15/15℃ (suboptimal temperatures, SOTs). Contrary to expectations, SOTs did not significantly increase petal number compared to OT. Instead, SOTs significantly increased stamen and carpel numbers by 1.3- and 2-fold, respectively, resulting in a 1.4-fold increase in total floral organ formation. To elucidate the rise in the number of reproductive organs, we performed qRT-PCR for floral organ identity genes and transcriptome analysis. The mRNA levels of the A-class genes (RhAP1** and RhFUL**) and the D-class gene (RhSHP* ) were increased, while the B-class gene (RhPI* ) was suppressed. However, the C-class gene (RhAG) did not show significant expression under the SOTs. A total of 1,143 common DEGs were detected under 15/15℃ (SOT) compared to 25/20℃ (OT). The up-regulated DEGs are primarily involved in transcriptional regulation, while the down-regulated DEGs are associated with signaling and secondary metabolic synthesis. In addition, we observed expanded floral meristems due to the prolonged duration of floral meristem termination under the SOT. Although we expected an increase in the number of reproductive organs interacting with floral meristem termination, significant FMT-related genes (WUS, YUC) were not identified in the transcriptome analysis. Further research is needed to explore the effects of various factors involved in floral organogenesis under low temperatures. These results suggest that SOTs enhance carpel organogenesis during flowering, indicating the involvement of various factors in floral organogenesis by flower traits.