I want to know about Coleus forskohlii a plant of South Africa. What growing conditions does it need, and what are its medicinal properties?
The plant you ask about is Coleus forskohlii (also known as Plectranthus forskohlii) in the family of plants called Lamiaceae. If your growing conditions resemble those of its native range (it grows wild in parts of West Bengal), you may be able to grow this plant.
The article entitled “Development of Coleus forskohlii as a medicinal crop” (no longer available online) from the Food and Agriculture Organization gives much information of interest. Here is an excerpt:
Coleus forskohlii grows wild on sun-exposed arid and semi-arid hill slopes of the Himalayas from Simla eastward to Sikkim and Bhutan, Deccan Plateau, Eastern Ghats, Eastern Plateau and rainshadow regions of the Western Ghats in India. Latitudinal and altitudinal range for the occurrence of the species is between 8 degrees and 31 degrees N and 600-800 m respectively. The species was studied for its ecological preferences in its native habitats throughout its distribution range excluding Eastern Plateau, Sikkim and Bhutan. Before the botanical studies were undertaken, the species was studied in the regional floras and herbarium specimens were examined in seven zonal herbaria of the botanical survey of India at Dehra Dun (Himalayan flora), Allahabad (Central India flora), Shillong (northeastern India flora), Jodhpur (Rajasthan flora), Pune (western India flora), Coimbatore (southern India flora) and Port Blair (Andaman and Nicobar group of islands flora), as well as at the Forest Research Institute, Dehra Dun and the Blatter Herbarium in Bombay. Eleven representative ecogeographic areas were selected for habitat and population studies; between 1982 and 1985, 27 botanical trips were made for the purpose. Coleus-growing areas in the Himalayas in Uttar Pradesh were visited every month from April to December, and the other areas were visited at least twice during the blooming period. The following is the summary of the observations made on different populations and habitats of C. forskohlii (Shah 1989).
C. forskohlii is a subtropical and warm temperate species naturally growing at 600-1800 m elevation
The species grows on sun-exposed hill slopes and plateaus in arid and semi-arid climatic zones
The species inhabits loamy or sandy-loam soil with 6.4 to 7.9 pH
The species is herbaceous with annual stems and perennial rootstock
The medicinal uses of this plant have not been evaluated fully for safety. Sloan-Kettering Cancer Center also has useful information about Coleus forskohlii. Here is a brief excerpt: “Very limited data are available concerning the efficacy of forskolin. Most studies performed with forskolin have been human trials; those performed on heart failure and glaucoma are inconclusive.”
As with any drug or herbal medicine, you should consult a medical professional if you have questions about its use.