Tu BiSh'vat or the "New Year of the Trees" is Jewish Arbor Day. The holiday is observed on the 15th (tu) of the Hebrew month of Sh'vat. Scholars believe that originally Tu BiSh'vat was an agricultural festival, marking the emergence of spring. In the 17th century, Kabbalists created a ritual for Tu BiSh'vat that is similar to a Passover seder. Today, many Jews hold a modern version of the Tu BiSh'vat seder each year. The holiday also has become a tree-planting festival in Israel, in which Israelis and Jews around the world plant trees in honor or in memory of loved ones and friends.