When did vampires become weak to roses?
had to check, well, it says its once believe it is. here's what it quote:
"It was once believed by many that the fragrance of a rose would ward off all evil, including not just vampires, but witches and werewolves as well. While the aroma repelled them, the petals were said to burn a vampire’s skin like acid. In Romania, placing wild rose on a corpse was believed to keep it from returning as a vampire."