“The dead receive more flowers than the living, because regret is stronger than gratitude.”

Anne Frank never actually wrote that, or anything close to it, although a lot of websites claim she did. Snopes could not find it in her writings nor any record of the saying prior to a Tumblr post in the early 2000's. Anne Frank Fonds, her legal heir, confirmed that she never wrote nor said that to her knowledge.

The saying, though, has merit whether you say regret or guilt. Gratitude you can always procrastinate on it, figuring you can show it tomorrow. But once they are dead, the regret and guilt sets in for your procrastination and flowers is the most ostentatious way of showing it.