I was also interested in portraying flowers at other stages in decay. The first test I did was to burn the flowers and see if that produced anything visually appealing.
Burning living flowers had little results, as the flowers are too wet to burn properly.
Burning dead/dried flowers had a much better outcome. In some places the flowers turned white, which was contrasted against the black of the burned petals.
I also took a few videos of the flowers burning up. This would be good reference material if I choose to portray burning flowers at different stages.