I’ve had a Kumquat tree for about 5 years and have never had any fruit. I have a Kafir Lime as well which leaves are prolific, but should it have fruit too?
Both Kamquat and Kafir Lime can take anywhere up to 5-6 years after planting before they fruit. If your Kamquat tree is grown in a container it’s possible that at flowering or early fruit forming stage it may have dried out causing the flowers or young fruit to fall off. However if the tree appears to be growing healthy and sturdily, then it is just a matter of time before the tree begins to bear fruit.
Feed it with side dressings of Daltons incredible edibles® Citrus fertiliser at 6 weekly intervals from late October to December, recommencing March/April till early May. Ensure the tree is well watered during the growing season. Regarding your Kafir Lime; as the plant matures the very unusual looking fruit (like a wrinkly lime) will appear. For culinary purposes, it’s the leaf rather than the fruit that is important. To keep the tree healthy with glossy leaves, apply side dressings of a citrus fertiliser as above.