For the past 4 years, I've had two Musa Banana dwarf trees indoors. This year I finally decided to throw both of them outside for the summer. One tree was 8' tall and the other was 6'. They grow pretty quick, however, do not produce anything yet. A week ago, I cut both of them down to the ground (pot) knowing that both plants produced new tree sprouts coming up from the soil. Why aren't they producing bananas when mature ?