Why does my photoshopped flower look unnatural please?

In this photo i have photshopped the flower that is circled. It was a more orange colour and for some reason the end result doesn't look natural like the other flowers.

The following are the steps that i used:

*Created new layer

*Isolated the flower roughly with polyglonal lasoo so other areas would not be affected

*Used the colour dropper on the pink flower next to it to select from

*Painted over the flower i wanted to change

*chnaged from normal to colour (right side of screen)

Image -adjustment-curves and saturation etc

Thew end result looks somehow like decolourised black and white photo or something?

But, if i increase the saturation it just turns an unnatural gharish shades of pink.

Somehow all my attempts always look either gharish colours or faded - like look.

Photoshop is harder and more of an artform then i realised it would be!

Thanks!

(original photo below)