The Jewish people gave trees a place of honor in the Jewish calendar. The scholars of the Mishna were greatly concerned with the date. Beit Hillel and Beit Shamai were divided on the issue of the date on which plants awaken from their winter hibernation and start to feed on the rains of the new year.

"The first of Shvat is the arbor new year", said Beit Shamai. "The fifteenth," responded the Beit Hillel.
(The Mishna of Rosh Hashana, A)

It was the ruling of Beit Hillel that was finally adopted.

Trees have been viewed both as an existential value and a symbol since the Jewish tribes approached the Land of Israel: "When you shall come to the Land, you shall plant all types of trees"
(Leviticus 19:2-3)

The prophet Isaiah spoke of the planting of trees when he spoke to the people of their permanent return to the homeland: "And you shall build houses and dwell there and plant vineyards and eat their fruit... because the life of my people is like a tree."
(Isaiah 65:21-22)

The sages also used the tree in order to describe the renaissance of the people and their renewed ties with the land: "The days of the people are like the days of the tree - like this Sycamore, growing in the land."
(Bereishit Rabba 12:6)
The Sycamore symbolized the longevity of life and ability to survive under difficult condition.

The custom in Eretz Yisrael was to plant a tree whenever a child was born: a Cedar for a boy, a Cypress tree for a girl. (Babylonian Talmud, Gittin 57 p. 1) After the people was exiled from the Land of Israel, the physical connection between man, trees and the earth turned into one of consciousness. Hymns were written in honor of the holiday and various traditions and customs were set.

When Rabbi Isaac Lurie and his associates founded the Jewish center in Safed, they established 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.

The Kabbalists added to the eating of fruit a special Seder on the eve of the 15th of Shvat, at which four glasses of wine - symbolizing the four seasons - were drunk, and chapters from the sources, about nature and the land, were studied. The Seder was ended with dancing.

When the Zionist pioneers started to settle in Eretz Yisrael at the end of the 19th century, afforestation activities, to redeem the land from its barrenness, began. On the 15th of Shvat in 1892, the educator Ze`ev Ya'avets took his pupils to plant trees in Zichron Ya'acov. In 1908 the Jewish National Fund and Jewish education system, adopted the custom of school children and their teachers going out to the fields and mountains to plant saplings. The planting of trees was turned into a symbol of the participation of the individual in the national project of redemption, as in the olden days when Rabbi Yohanan Ben Zakai said:
"If you have a sapling in your hand and are told that the Messiah has arrived - plant the sapling and then go to greet him."
(Avoth DeRabbi Nathan' b' ch.31).

During the planting of the President's Forest in 1949, Prime Minister David Ben Gurion said:
"Of all the blessed acts in which we are engaged in this country, I do not know if there is a more fruitful enterprise, whose results are so useful, as the planting of trees, which adds beauty to the scenery of our country, improves its climate and adds health to its inhabitants."

It was no coincidence that the 15th of Shvat - the day which symbolizes the revival of nature, as highlighted by the flowering of the almond trees, and of the renewed ties between the Jewish people and its land - was chosen by various institutions as their inauguration day:
The cornerstone of the Hebrew University in Jerusalem was laid in 1918; the Technion in Haifa in 1925; The Knesset - the Parliament of Israel in 1949.