How do you dead head petunias?
Dead heading any flower is simply pinching (or cutting) off the dead flower once it has faded from it's bloom. A dead flower that is left on the bush and is developing seeds, sends a chemical signal through out the plant which lets the plant know that seed production is in full swing, and the plant doesn't have to keep producing flowers. Most gardeners WANT the flowers (not the seeds) so dead heading prolongs the blooming season.
use pruners or scissors.