Coleus forskohlii grows in the wild in warm subtropical temperate regions of India, Nepal, Burma, Sri Lanka and Thailand. Apparently, it has been distributed to Egypt, Arabia, Ethiopia, tropical East Africa and Brazil, as well. In India wild Coleus forskohlii is found mostly on the dry and barren hills. Latitudinal and altitudinal range for the occurrence of the species is between 8°- 31°N and 600-800 m, respectively.
Since medicinal plants form the major resource base of our indigenous health care traditions, Sami/Sabinsa group also pioneered cultivation efforts for the plant, based on varieties and techniques, developed through focused research, targeting the promotion of “green” practices and sustainability. Sami/Sabinsa group, a company that is technology-driven as well as environmentally responsible manufacturer of herbal ingredients, adopted tissue culture as an enabling technology to maintain a sustainable source of Coleus forskohlii roots.
This approach has ensured us pathogen-free, disease-indexed and high yielding planting material of Coleus forskohlii, which further helped to increase the yield, productivity, uniformity of produce and reduced harvesting time and wastage. This resulted in the development of premium quality planting material and established protocols for the micropropagation, which further enabled us to transfer the “rooted cuttings” of Coleus, developed through tissue culture technology, to the farmers, who are reaping encouraging results.
Furthermore, the group extensively studied the field performances of rooted cuttings and seedlings and has been found that vegetatively propagated planting stock had higher field growth performance than seedling. Rooted cuttings had good survival rate and grew well in the field.
According to Kavitha et al. (2010), Coleus forskohlii is propagated by seeds as well as vegetatively by terminal stem cuttings. Because seed propagation is difficult and slow, propagation by terminal stem cutting is easy and economical. Cultivation practice involves planting of terminal cuttings of 10–12 cm length with 3–4 pairs of leaves in nursery beds to induce rooting.
When the 1-month-old cuttings have produced sufficient roots, they are transplanted to the main field. The best period of planting in South India is during the month of June and July, and during September to October. Rooted cuttings are planted at an interval of 60 cm. Proper irrigation methods, weeding and plant protection should be adopted. The forskolin content of the roots obtained from natural habitats ranges from 0.04–0.6% of dry cell weight, 0.5% being the most common.