[Tu B’Shvat] Tu Bishvat (Hebrew: ט״ו בשבט) is a minor Jewish holiday, occurring on the 15th day of the Hebrew month of Shevat. It is also called “The New Year of the Trees” or (Hebrew: ראש השנה לאילנות, Rosh HaShanah La’Ilanot). Tu Bishvat is one of four “New Years” mentioned in the Mishnah.  This year, it will fall upon the dusk of January 15 through the dusk of January 16, 2014.
The name Tu Bishvat is derived from the Hebrew date of the holiday, which occurs on the fifteenth day of Shevat. “Tu” stands for the Hebrew letters Tet and Vav, which together have the numerical value of 9 and 6, adding up to 15.
Tu Bishvat generally falls on the second full moon before Passover, or, in a leap year, the third full moon before Passover.
In the synagogue, the penitential prayer of Tachanun is omitted on Tu Bishvat (and at the afternoon service of the day before), as is the custom on minor Jewish holidays. There are no other special recitations or blessings in the prayer service.
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 Israel, the kabbalistic Tu Bishvat seder has been revived, and is now celebrated by many Jews, religious and secular. Special haggadot have been written for this purpose.
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.
On Tu Bishvat 1890, Rabbi Zeev Yavetz, one of the founders of the Mizrachi movement, took his students to plant trees in the agricultural colony of Zichron Yaakov. This custom was adopted in 1908 by the Jewish Teachers Union and later by the Jewish National Fund (Keren HaKayemet L’Israel), established in 1901 to oversee land reclamation and afforestation of the Land of Israel. In the early 20th century, the Jewish National Fund devoted the day to planting eucalyptus trees to stop the plague of malaria in the Hula Valley; today the Fund schedules major tree-planting events in large forests every Tu Bishvat . Over a million Israelis take part in the Jewish National Fund’s Tu Bishvat tree-planting activities.
In keeping with the idea of Tu Bishvat marking the revival of nature, many of Israel’s major institutions have chosen this day for their inauguration. The cornerstone-laying of the Hebrew University of Jerusalem took place on Tu Bishvat 1918; the Technion in Haifa, on Tu Bishvat 1925; and the Knesset, on Tu Bishvat 1949.
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. On Israeli kibbutzim, Tu Bishvat is celebrated as an agricultural holiday.
^ 1. Rosh Hashanah 2a.
^ 2.When representing the number using letters, rabbinic rules forbid using the letter-numerals that represent 10 (י Yud) and 5 (הHei) together because they form the abbreviation of the “ineffable name of God”, YHVH יהוה. Therefore, the number 15 is represented by the letters ט (Tet) and ו (Vav), or 9 and 6 = 15.
^ 3. Ateret Cohanim
^ 4. Tu B’Shevat on Virtual Jerusalem
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^ 6. “Zionist Philosophies”. Mfa.gov.il. 1999-10-19. Retrieved 2011-01-20.
^ 7. Zuroff, Rabbi Avraham (2011). “Just a Jewish Arbor Day?”. Ohr Somayach International. Retrieved 20 January 2011.
^ 8. a b Rinat, Zafrir (20 January 2011). “Israelis Go Green For Tu Bishvat”. Haaretz. Retrieved 20 January 2011.
^ 9. Paz, Shelly (2008-01-19). “Tu Bishvat gets ‘shmita’ treatment | Israel | Jerusalem Post”. Fr.jpost.com. Retrieved 2011-11-06.
^ 10 “The Knesset’s Early years”. Knesset.gov.il. Retrieved 2011-01-20.
^ 11. “Tu B’Shevat (Arbor Day) in United States”. Operational Home Front. 2011. Retrieved 20 January 2011.
^ 12. “Arbor Day Around the World”. Arbor Day Foundation. Retrieved 20 January 2011.
^ 13. “Kibbutz Lotan – Tu B’shvat Campaign”. Kibbutz Lotan. 2005. Retrieved 20 January 2011.
^ 14. “Tu B’Shvat – The Jewish Earth Day”. Jewish Woman Magazine. Retrieved 20 January 2011.
An excerpt from: http://en.wikipedia.org/wiki/Tu_Bishvat