I'm hoping someone can help me with a persistent problem I have with one of my citrus trees. I have now three citrus trees in containers: Lemon, Blood Orange, and Meyer Lemon. While what I would call my "traditional" lemon tree flowers and produces abundant fruit, the other two do not; one has never flowered, and the other produces quite large flowers which then fall without setting any fruit. All three are at least 8 years old. It flowers frequently too, so it's trying...! It is now flowering again, and I'm wondering if there is something I can do right now to encourage fruit to set. Thanks to all in advance!