20 foot is considered dwarf for mango trees. As was pointed out before, Julie will get 20 feet when mature if unpruned.
Yeah, my favorite ( so far ) tree which I have NO idea what the fruit is has stayed the same height for 11 years. About 12 - 15 feet. Great mango and very sweet even when half ripen. So I expect to maintain a tree that can grow to around 20 manageable feet.
That is to be expected. But man, I picked from a customers Valencia Pride and I remember tiring the back of my neck just trying to look at the mangoes at the top of the tree.
But I like this mango and the Keitt as big mangoes. The Keitt is so everywhere with it's growth pattern...