Why are my double tuberous begonias now producing single blooms?

Question

My double tuberous begonias are now producing single blossoms. Flowers are healthy, color good, no droop. Too much shade? water? What do I do?

Answer 1

This is the case without fertilizing these heavy feeders properly.
This article will help you.
https://www.gardeningknowhow.com/ornamental/flowers/begonia/tuberous-begonia-fertilizing.htm