Tu BiShvat, or the "New Year of the Trees," is a Jewish holiday celebrated on the 15th of Shevat in the Hebrew calendar.
Tu BiShvat is named after its occurrence on the fifteenth day of Shevat in the Hebrew calendar. "Tu" represents the Hebrew letters Tes and Vav, which numerically equal 15. It is also called "Chamisha Asar BiShvat," meaning 'Fifteenth of Shevat.'
Tu BiShvat, mentioned in the Mishnah's Tractate Rosh Hashanah, is one of the four new years in the Jewish calendar. The Academy of Shammai posited the new year for trees on the first of Shevat, while the Academy of Hillel placed it on the fifteenth. The Rabbi's sided with Hillel, establishing the 15th of Shevat as the start of the agricultural cycle for biblical tithes.
Tu BiShvat is crucial for determining the status of biblical tithes, such as Orlah, Neta Reva'i, the second tithe, and the impoverished tithe, based on fruit ripening in relation to this date.
Tu BiShvat, occurring on the 15th of the Hebrew month of Shevat, initiates a series of mid-month full moon holidays, culminating in Passover.
In the 16th century, Rabbi Yitzchak Luria of Tzfas (Arizal) and his disciples established a Tu BiShvat seder. This meal involved eating specific fruits and drinking four cups of wine in a set order, with symbolic meanings attributed to the fruits and trees of Israel, particularly the Seven Species.
The kabbalistic Tu BiShvat seder has been relatively revived and is now occasionally celebrated by Jews, with special Haggados written for the occasion.
In some Chasidic communities, Jews pickle or candy the esrog from Sukkos and eat it on Tu BiShvat. Many use this unique day to pray that they will be worthy of a beautiful esrog on the following Sukkos.
Some Sephardic Jews prepare a dessert made of grains, dried fruits, and nuts, known as Ashure or trigo koço, to honor the holiday.
Another rare custom involves drinking both red and white wines to symbolize the transition from winter to spring.