From the original image, make another copy and desaturate it.
Then adjust the level until you get the desired amount of black and white on the picture.
From there, make it as a layer mask and mask everything except one of the petal.
Flatten the image and make a copy of it again.
Then use smart blur on max setting and unsharp image on normal setting, you'll get a stronger colour.
Apply gaussian blur a little bit to give the smooth feeling.
Flatten it again and make another copy.
Apply gaussian blur again to create the depth.
Make it as a layer mask and mask everything using the radial gradient tool. You'll get a center-focused depth.
-end-

This is the original image!