Yes, you can send flowers to your ex after a breakup. However, you should follow certain etiquette. You should send only once or a maximum of two times. If the other person wants to come into your life again, they will accept it in the first two attempts. You can also add a simple message of apology or say that "I'm ashamed and sorry for my actions and behaviour," or "I love you," or "please come back." Sometimes, people do not recommend sending flowers after a breakup because it is not ethically good. In conclusion, it depends upon how your relationship ended. So, you can decide whether sending a bouquet makes any difference or not.