They grow well in full sun as well as in shade. But for the best result, you should keep your potted plant in a place where it gets early morning sunlight and mid-afternoon shade. This is because: In the early morning, the sunlight is not strong and gives a freshness to the bloom whereas in the mid-afternoon the sunlight and heat are way stronger that may damage the bloom. So I recommend you place potted begonias in a spot where they get early morning light and mid-afternoon shade.