According to The Book of Formation (Sefer Yetzirah)
Each month of the Jewish year has a corresponding color, a letter of the Hebrew alphabet, a zodiac sign, one of the twelve tribes of Israel, a sense, and a controlling organ/limb of the body.
Shvat is the eleventh of the twelve months of the Jewish calendar.
The 15th day of Shevat-Tu Beeshvat-is the "New Year of Trees" according to the school of Hillel; according to the school of Shamai, the "New Year of Trees" is the first of Shevat. The "New Year of Trees" is the day from which the new year is reckoned for the fruit of the trees with regard to the mitzvot of ma'aser ("tithes"; fruit that blossoms after this date may not be taken as a tithe with fruit that blossomed before) and orlah (the fruit of a tree less than three years old is called orlah, and is forbidden to eat). Tu Beeshvat is celebrated by partaking of fruit, especially of the seven species with which the land of Israel is blessed.
Tu Beeshvat, the 15th day of the 11th month alludes to the secret of God's essential Name, Havayah (י־הוה). The value of the first two letters of Havayah, (the yud and hei, which represent the higher, concealed level of unification) is 15. Its last two letters (vav and hei, which represent the lower, revealed level of unification), equal 11. Indeed, as explained elsewhere, the full secret of the Havayah is the secret of the "Tree of Life," the tree of the month of Shevat.
Letter: Tzadik - צ
The letter tzadik (צ) symbolizes the true tzadik ("righteous one"), "and the tzadik is the foundation of the world." The one consummate tzadik of the generation personifies the Tree of Life in the Garden of Eden (all of whose trees correspond to the souls of the righteous).
The very form of the letter tzadik (especially its final form, ץ, which represents the true manifestation of the tzadik in the future) resembles a tree. In the Torah, man is called "the tree of the field" (עֵץ הַשָׂדֶה), which equals 474. 474 is also the gematria of "knowledge" (דַעַת), the unique property of man in general and of the tzadik in particular. The word "knowledge" in Hebrew implies the power of "connection." Thus, the month of Shevat is the month for connecting to the true tzadik of the generation, the Tree of Life of the generation.
In Hebrew: שְׁבַט
Mazal: D'li (Aquarius--the Pail)
The New Year of Trees of the month of Shevat is the time that the rain waters of the winter months begin to ascend in the veins of the tree and bring it new life. The ascent of water in general is represented by the "pail" (דְלִי), which in Hebrew steams from the root meaning "to lift up," as in the verse "my eyes are lifted up to heaven" (Isaiah 38:14). The letter of the previous month, Tevet, is the ayin (ע), which literally means "an eye." When the ayin of Tevet is lifted up to connect with the tzadik of Shevat, the word "tree" (עֵץ) is formed.
The Ba'al Shem Tov said that when one meets a water-carrier carrying pitchers full of water, it is a sign of blessing. The tzadik is considered the true manifestation of a water carrier.
"'Water' refers to Torah." The month of Shevat is referred to as the new year for the study of Torah. The eating of the fruits of Shevat corresponds to the partaking of and integration of the sweet fruits of Torah wisdom. And so the waters of Shevat represent the sweet waters of Torah.