Begonias are great houseplants,very easily maintained.
I would recommend keeping them outdoors in the shade during the summer months,and keep them evenly moist.
They will benefit from a light misting about twice a week,and apply a mild fungicide to combat powdery mildew.
They can actually become dry for a few days provided they are established and healthy.

Escargot is a Rex begonia, won't stand sun at all....while "wax" begonias will do well in all day sun, if well watered.
did you repot it? It needs well drained soil which will allow you to water it fairly often and allow the water to drain.
Linda C

I repotted the begonias from the plastic nursery pots into decorative ceramic pots of the same size, with drainage holes. Maybe I should try putting them outside??

Is your soilw elld rained?
They would love a shady spot outside.
Linda C