This paper describes an efficient colchicine-mediated technique for in vitro induction of octoploids in Pogostemon cablin and its confirmation by flow cytometry and chromosome numbers. The highest octoploid induction ratio was obtained by 0.05% colchicine treatment for 72 h. The chromosome number of octoploid seedlings was 2n = 8x = 128. Colchicine-induced tetraploids and octoploids planted in soil remained stable after 6 months. There were 31 lines of octoploid plants obtained. The leaf characteristics of P. cablin tetraploids and octoploids were compared. The larger leaves and stomata of transplants can be used to identify putative octoploids in P. cablin. Most octoploid lines exhibited higher patchoulic alcohol contents than the controls after 6 months of cultivation. Our results demonstrated that polyploidy induction can be beneficial in improving the medicinal value of P. cablin.