Tu - Bishvat is the ancient Jewish new year of the trees. It is celebrated on the fifteenth of the month of Shvat of the Hebrew lunar calendar. This usually falls in February or late January. The name Tu Bisvhat means fifteenth of Shvat (Tu-bi-Shvat). "Tet vav" in the Hebrew numbering system is fifteen.  The "vav" becomes a vowel - "oo."  In ancient times Tu Bishvat was a harvest holiday that may have been started for tax purposes.

Tu-Bishvat was celebrated during the long years of the Diaspora, but the rise of Zionism and the hope of returning to the homeland gave new meanings and new life to Tu Bishvat. The Zionist movement undertook a vast project of land redemption on the barren hillsides of the holy land. Trees purchased by tiny contributions of Jews all over the world helped turn the overgrazed and rocky slopes into forests. Tu Bishvat assumed a special significance in the life of the Jewish community in Israel. The hillsides of Judea and the Galilee had been stripped of tree cover. Hydrogeologists and agronomists believed that planting trees would help increase rainfall in this dry land, and tree roots would help retain water and anchor soil on eroded hillsides. In swampy areas, eucalyptus trees were needed to absorb water. Tu Bishvat became a symbol of the massive reforestation effort. Each year on Tu Bishvat, since 1908, Israeli school children and adults participate in tree planting ceremonies throughout Israel. As a result of the reforestation effort, Israel is the only country in the world that has more tree cover at the beginning of the twenty-first century than it did at the beginning of the twentieth century. 

The Mishna (ancient law book) states:

Rabbi Hillel and Rabbi Shamai represented different schools of legal opinion. The opinion of Hillel came to be accepted. Fruit picked until the 15th of Shvat was counted for tithing that year. Fruit picked from the trees after Tu Bishvat was counted for the following year.

After the Jews were exiled from Israel and stopped engaging in agriculture, the holiday lost its significance. However, when Rabbi Isaac Lurie and his students founded a Jewish community in Safed in the Galilee, they started the custom of eating fruit on the 15th of Shvat, as a symbol of man's participation in the joy of the trees. This custom soon spread amongst all the Jewish communities. In the 16th Century others started a tradition of celebrating a Tu Bishvat Seder or festive meal.