I have a Lancetilla Mango, approx. 15-20 ft tall now.... this has been my best year yet for fruit, with about 2 dozen GIANT mangos hanging like footballs.... but they are still very green and rock hard. A couple have started just the tiniest bit of red blush... but 8 or 10 have fallen from the tree, completely green. I've tried leaving them in a paper bag, as well as out in the sun... but they won't ripen.