White Hydrangeas are turning green surrounded by the center of the blossoms, what is wrong? I have an indoor white hydrangea plant that have fully bloomed...

I have an indoor white hydrangea plant that have fully bloomed and is now the blossoms are turning green. The plant get watered often (the soil is other damp) and it sits in the glass recieving half direct sunlight.
I want to know, am I over watering them, too much sun, what is wrong near it? Or is nothing wrong and this is only normal?
Answers:    Hyrdrangeas turn colors base on what is in the soil...so if in that is alot of acid or neutralizer surrounded by the soil, it will affect the color.

Either way, as long as they look wholesome, then it is faultlessly normal.
Normal for the indoor choice