My Plants And Fruit Tree (guava, Wax Apple And Solanum) Always Flowering But Never Had Fruit, Why?

Answer 1

This is, typically, due to there being too much nitrogen or not enough phosphorus and potassium in the soil. I would be sure to test the soil and pH, then amend accordingly.

These articles will help:

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/testing-soil.htm

https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/soil-ph-plants.htm