I know that Bustan means a green and lush place, and since Boston is such a place, I thought perhaps when the colony was founded the founders thought of calling it so.
My Oxford Dictionary of English Place Names (OUP 1998) disagrees with this. It says that the first mention of Boston is as “Botuluestan“ in a document of 1130. It says the name means “stone (marking a boundary or meeting place) of a man called Bōtwulf. Identification of Bōtwulf with the 7th century missionary St Botulph is improbable”."Boston" meant Botolph's Town.