Our lime tree is six years old now and has started to grow limes, but they are yellow. Our lemon tree is about 12 feet away from our lime tree and is doing well. The leaves on the lime tree when pulled off smells like a lime.
Certified GKH Gardening Expert
If the limes are yellow, they have been left on the tree too long. Limes are actually picked while green and are yellow once they've fully matured. This article explains more: https://www.gardeningknowhow.com/edible/fruits/lime/lime-tree-harvest-time-when-to-pick-a-lime-from-a-tree.htm