Banaba Production in the UK

I have been looking with interest into the benefits of Banaba and the research conducted, particularily by the Japanese into the benefits of this herb with a view to potentially conduct a growth trial. We solely use hydroponic systems and have a good idea which types we would use. However I am having difficulty procuring research material pertaining to the details in cultivating Banaba much of what I have found is vague and inconsistent. If you could affirm any of the following it would be greatly appreciated.
Generally how old would a Banaba bush/tree be when the leaves are harvested in a wildcrafted scenario? Is it only the tree variety that would supply the required actives or would the bush also provide what we need? Over what time period does the bush reach maturity?Could you recommend a direction to look in to ascertain further details on the cultivation of this herb?

Banaba (Lagerstroemia speciosa) is a medium-sized tree that grows in disturbed or secondary forests throughout southeast Asia. The Philippines is a commercial source of the leaf, where the herb is used medicinally, notably for diabetes. Supplements based on banaba are currently marketed in the U.S. and Europe.
We do not have the answer to your question about wildcrafting of banaba and the age of the trees. I suggest that you contact the Philippine Council for Agriculture, Forestry and Natural Resources Research and Development. At that organization's Farmer's Information and Technology Services Information System website (https://opendbs.pcarrd.dost.gov.ph/fits/index.php) you can access databases of farmers and experts for a variety of commodities. Although, banaba is not specifically included in the database (at least as far I can tell) you may be able to contact people who can answer your question accurately through leads found there. Because little has been published about the commercial aspects of this herb it is advisable to try to find people with direct knowledge of the harvesting practices of the herb.
Another useful source of information for details on cultivation of tropical trees is the AgroForestry Tree Database which is maintained by the World Agroforestry Centre in Kenya. The database entry on Lagerstroemia speciosa is found at:
www.worldagroforestrycentre.org/Sea/Products/AFDbases/AF/asp/SpeciesInfo.asp?SpID=1790
The World Agroforestry Centre may also be able to direct you to experts with direct knowledge of the crop. The Centre has regional offices in Asia and elsewhere.