What Causes Color Change in Limes
My dwarf lime tree had more fruit this year than ever before. However, the limes never turned green. When they dropped off the tree, they were still yellow on the outside. There are no more limes on the tree now, but it is full of blossoms and looks absolutely beautiful. Any clue as to why the fruit did not turn green?
Certified GKH Gardening Expert
Limes do not turn green. They start out that way and turn yellow as they ripen. Limes are actually taken prior to their turning yellow. If your limes remained yellow, either they were left on the tree too long or you have a lemon tree rather than a lime tree.
This articles will also help: https://www.gardeningknowhow.com/edible/fruits/lime/is-lime-fruit-and-lime-blossoms-falling-off-tree-normal.htm