Tissue culture is generally used for the proliferation of trees with genetically identical characteristics. However, since required nutrients vary among trees, it is necessary to prepare culture media appropriate to each kind of tree. Furthermore, reagents such as growth -controlling substances can be expensive depending on the kind of tree. In this study, we examined a method of enhancing the growth of trees by adding carbon dioxide irrespective of the type of culture media. Carbon dioxide was generated by dissolving commercially available bath conditioners, and experiments were performed using 2 kinds of culture media with and without carbon dioxide. The samples were about 10 mm-long pieces of Prunus x saihoziensis, subcultured since 1996, with axillary buds. The growth of shoots and rooting rate was examined one month after the start of experiments, and the effects of added carbon dioxide were examined. Positive effects of carbon dioxide were noted.