Nope, I think the background is reasonably natural. I can't tell for sure if this is a gallardia or dahalia, but it looks pretty and cheerful. Very nice shot.
The picture is a great shot. The flower is in focus. But I believe that instead of darking the background you should of lessen the saturation a bit. Cause the green background would also be good. But the if the background has more of brown color then green, then I believe that your effect is up to the mark. Good Capture ;-)
I think it's a great shot. That is an interesting yellow ring that forms around the edge. I don't think you went too far for the darkening, but I might saturate the green in background just a bit, but not too much to detract from the flower.