I grew several trees from my grapefruit tree seeds and planted one on some land we have. While it is doing well (with a diet of fish crap from my filter) it would probably be even better if it weren't for all the caterpillars and such munching on the leaves. I grew this tree in a pot in Dec 2014 and transplanted it last year, it has tripled in size since then. But you can see where leaves are being eaten. I believe red ants would protect the tree, but since the tree is doing well on its own I'd rather not have the ants.
Lucky that buffalos don't eat the tree. Notice that ground is fairly clear of plant growth not because we cut it but because Thai graze their cattle on it.
I added a pic from just after we planted it.