We have developed optimum culture conditions for the large-scale propagation of chrysanthemum in balloon-type bioreactors to achieve vigorous growth and quality. The effects of NH₄ /NO₃⁻ ratio, air volume, air temperature, photosynthetic photo flux, and an inoculation density on the growth and quality of plantlets were investigated. The best production conditions were an NH₄ :NO₃⁻ ratio of 20:40 mM, air exchange of 0.1 vvm min⁻¹, air temperature 25°C, photosynthetic photo flux (PPF) at 100 μmol m⁻² s⁻¹, and an inoculation density of 40 nodes Chrysanthemum grandiflorum. Under each of these conditions, the maximum growth rate reached 279.0, 260.0, 20.0, 23.3, and 94.5 (g-fresh weight per plantlet d⁻¹), respectively, at 12 wk of culture. These results specify the key environmental factors that can be regulated to improve the quality and quantity of flowers and increase yield in large-scale bioreactor cultures of chrysanthemum.