This article discusses problems associated with the cultivation of medicinal plants for the production of phytopharmaceuticals. To ensure the efficacy and safety of these phytopharmaceutical products or medicinal components, it is necessary to cultivate medicinal plants under controlled environments. This method of cultivation can also ensure the optimum environment and nutrient composition to maximize biomass production as well as medicinal components. When plants are under stress, the production of medicinal components may increase because plant growth is often inhibited more than photosynthesis, and so the carbon that is fixed but not allocated to growth is instead allocated to medicinal components production. Temperature and water stresses are described in this chapter. The impact of the spectral quality of light and ultraviolet radiation on plants under controlled environments on the production of medicinal metabolites are also discussed.