Manual deflowering and leaf maturity were evaluated for effect on the yields of the bioactive sennosides A and B in Tinnevelly senna (Cassia angustifolia Vahl). Deflowering increased sennoside A and B concentration (percent dry weight) in leaves by 25%, the total leaf dry mass by 63%, and the harvest index by 22%, with the result that the sennoside A and B yield (grams) per plant doubled in response to deflowering. During the same time, net photosynthesis remained consistently lower in the deflowered plants. Youngest leaves had the greatest sennoside A and B concentration. A clone raised from cuttings of one seedling had lower sennoside A:B ratio than the plants raised from the seedlings. Although crop type and possibly environmental conditions influenced the sennoside A:B ratio, deflowering and leaf maturity had no effect. The sennoside A and B concentrations in the dried leaves of deflowered plants harvested in 1.5-hour intervals appeared to increase during the course of the day. Deflowering, harvesting of young leaves, and harvesting time of day constitute promising component technologies for field investigations.