The following is an excerpt from Jimmy Akin’s FAQ on Ash Wednesday:
Q: Why are ashes from the previous year’s Palm Sunday used?
A: “Because Palm Sunday was when the people rejoiced at Jesus’ triumphal entrance to Jerusalem. They celebrated his arrival by waving palm fronds, little realizing that he was coming to die for their sins. By using palms from Palm Sunday, it is a reminder that we must not only rejoice of Jesus’ coming but also regret the fact that our sins made it necessary for him to die for us in order to save us from hell.”
The practice of using ashes from the previous year’s Palm Sunday began around the eighth century. For more information on this see:
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