If you were to choose a location in the US best for starting a pennywort farm, where should you start one? What's the best climate?
Centella asiatica, commonly known as centella, gotu kola, Asiatic or Indian pennywort, and Asiatic coinwort, is hardy to USDA zone 8, meaning it cannot tolerate temperatures below about 25° F. This plant is native to parts of India, China, Indonesia, Sri Lanka, the western South Sea Islands, Australia, Madagascar, and southern and middle Africa.
Centella asiatica prefers sun or partial shade and moist to wet soil. It flourishes in and around water and damp swampy areas, and in India is grows wild in damp, shady places and along marshy banks of rivers, streams, ponds, and irrigated fields. It grows and spreads very well outdoors during the summer and is very easy to increase by division, so it can be grown as a summer crop with divisions being taken during the growing season and overwintered in a greenhouse in areas north of zone 8.
In the Himalayas it grows up to an altitude of almost 7,000 feet. This is a versatile plant that could probably be farmed in many regions of the US as long as you are able to provide damp soil and warm air, which could be achieved inside a greenhouse for at least part of the year. One commercial grower (Avena Botanicals), for instance, is located in Maine.
Courtesy of NYBG Plant Information