Doesn't matter. With proper pruning practices, you can keep the mango well within the boundaries of your greenhouse.

Bihai
That would be true but a "dwarf"would be a much better choice. There are many types and cultivars which produce different tasting fruit and will produce at a much smaller size.
Ask Lisa over in the Florida forum she 's a nut for "dwarf" fruit trees. She can tell you sizes and names of the cultivars and a source.
gary

I bought a Nam Doc Thai patio mango at Lowes at 1/2 price a week or so ago [14.99] The tag says it gets to be 15'X 15'

The NamDoc's and the Manila's and all of that type are dwarf when grown in a container.Sort of. Four-five years of being in a pot holds them down to 6-9'. Pruning keeps them that way. But,they do bare tasty ,small Mangoe's ripening in late summer .
Mangoes grown where they don't grow are sure to A-maze.