thanks for reply.regdsSenna is cultivated during summer months. It is commonly grown as a rainfed crop in Thirunelvely, Madurai and Virudhunagar districts of Tamil Nadu.Leaf with good sennoside content(2.5%) will be produced only during April, may months,because more sunlight is required for the production this particular phytochemical in this herb. April - June is the suitable seasons for senna leaf harvest. There is so much demand for the leaves in the international market(more than 30000 ton ), the crop needs to be planned well in advance to get required quantity leaf. In Tuticorin senna mandies are available. If any body wants the considerable quantity dried leaf can get from there. During monsoon season it is cultivated in Rajasthan and Gujarat area also. Some northern part of Andhra pradesh and Karnataka it is cultivated, but there is no systematic market there. Senna fruit shell is also used as medicine,it contains more glycosides.Hence it costs more.