I want to the know the common or the commercial name of the plants Wikstroemia retusa --Gampi ( Japanese Name) Abelmoschus manihot --- Tororo aoi ( Japanese Name)
Abelmoschus manihot is Aibika, Sunset Muskmallow, or Sunset Hibiscus. Wikstroemia retusa is from a genus generally known as False Ohelo; you should be aware, though, that it's now called Daphne grayana; this would make it simply Daphne in English, and the Latin name will most likely be used in trade.
Aibika should; Daphne in general are considered weed species outside of their native ranges, but I'm not sure whether they'll do well in your more humid, tropical heat. Chennai is probably too far south for Daphne to thrive (if you were in, say Hamchal Pradesh, it would be another story entirely....) Maybe take a look at the Koppen-Geiger climate maps. Compare Chennai to the areas where Aibika and the Daphne are native. If they're within one KG zone of each other, there should be no problem growing them; more than three zones separation is pushing it. http://koeppen-geiger.vu-wien.ac.at/present.htm
