I live in hardiness zone 4, where not much can survive the winter, but I have been able to grow many tropical plants by bringing them inside before the frost, or by keeping them in my office year round.
I have 2 pineapple plants that are about 3 years old, a pomegranate tree that is about 6 years old, and an orange tree that is about 8 years old.
All of them are very healthy, and mature enough to fruit; the first pineapple plant even came with a pineapple growing when I bought it, but none have shown signs of flowering. I have read that fruiting depends on number of hours of daylight and day/night temperature cycles.
Is there a way I can coax the plants to flower and produce fruit?