But then you see the heavy shadow of the flower. It's a wonderful part of the composition. And we know that you don't see shadows like this in the sky. You are limited only by your imagination and the availability of supplies. Neutral colors like gray, black, white, and beige are good if the flower is very colorful.
Any light source can do.
If you're outdoors, consider natural sunlight. Indoors, you'll probably use flash. Just be aware of the possibility of a hard shadow, and decide in advance if you want your picture to include that shadow, or you want it to be outside the frame. The concentrated light of his on-camera flash gives sharp definition to the flowers. Further, because it's pitch-black out, the background is usually totally dark.