Tu Bishvat is a minor Jewish holiday, which is celebrated on January 31, 2018. It is occurring on the 15th day of the Hebrew month of Shevat. It is also called "Rosh HaShanah La'Ilanot", which means the "New Year of the Trees". Tu Bishvat is one of four "New Years" mentioned in the Mishnah. Tu Bishvat appears in the Mishnah in Tractate Rosh Hashanah as one of the four new years in the Jewish calendar. The discussion of when the New Year occurs was a source of debate among the rabbis.
In the Middle Ages, Tu Bishvat was celebrated with a feast of fruits in keeping with the Mishnaic description of the holiday as a "New Year." In the 16th century, the kabbalist Rabbi Yitzchak Luria of Safed and his disciples instituted a Tu Bishvat seder in which the fruits and trees of the Land of Israel were given symbolic meaning. The main idea was that eating ten specific fruits and drinking four cups of wine in a specific order while reciting the appropriate blessings would bring human beings, and the world, closer to spiritual perfection.
In the Chassidic community, some Jews pickle or candy the etrog (citron) from Sukkot and eat it on Tu Bishvat. Some pray that they will be worthy of a beautiful etrog on the following Sukkot. Tu Bishvat is considered by secular Israeli Jews and organizations to be the Jewish equivalent of Arbor Day, and it is often referred to by that name in international media. Ecological organizations in Israel and the diaspora have adopted the holiday to further environmental-awareness programs. (With material from: Wikipedia)