I love my dahlias. Not crazy about this shot.
a. It looks over processed in the bright bits and a not super job of painting in a black background.
b. Flowers don't float. I know some people take them out, but I prefer to have the stem in there to ground the shot.
Obviously I don't know the situation on this one, but if at all possible, learn to shoot the flower with a black background in the actual shot. It doesn't have to be much. My set up is a piece of black foam core in the shadows while the flower sits on my dining room table next to the window.