What are the indicators and signs of a cut flower that is dying or dead?

Well if ya need some help here it is. with roses the otter petals begin to wilt. I break them off and the rose will look newer longer, you have to keep the water clean and fresh with a few drops of bleach. Yes bleach. And cut the stems about an inch every few days, and do this under running water with a knife not scissors. Also, cut at an angle.