Why did our Sages call it Rosh HaShana for the Tree (and not Trees)? This question was not asked in the Talmud, but in one of the earliest Kabbalistic writings, the Zohar. By the way, an interesting fact is that most of the questions, asked by Sages in the Zohar, were answered not by others but by the "asker." The inner Torah teaches that everything we need to know is already inside ourselves. Every time the question is asked, our own soul gives an immediate answer, but in most cases we miss it, because we don't listen or there is a lot of other noise out there.

So, the answer in the Zohar was: "in the Mishnah it says the tree and not just trees, because they meant The Great Tree Le'eila (inside/above)." Meaning, there is some kind of ability inside us and in the spiritual world in general that can be called The Great Tree. But what does that mean? How are we supposed to recognize it and what are we supposed to do with that?

We started our journey as a people after the exodus from Egypt. We were newly-released slaves, walking for forty years in the desert. We began to form our communal consciousness in that physical and existential "lack". We learned to appreciate the ability to trust the unknown and unpredictable, to love the temporary, to experience the "here and now." We didn't plan, we didn't plant. We were fed "heavenly bread," the Manna. We didn't invest ourselves into anything but the journey itself. All of this experience had one main purpose – to teach us to let go of the illusion of control.

Those years in the desert represent the self-searching that every person is encouraged by Jewish tradition to go through, so we can learn to listen to the soft and powerful tune of our soul. Yes, it does help to put all those daily distractions aside. It may involve a certain level of detachment from the physical and the convenient.

But in Jewish tradition this detachment is temporary. It has never been our purpose to stay in the desert, even though some of the Israelites wanted to. There is a time to listen, and there is a time to express, to play the beautiful tune of our soul on all of our instruments. This is why we were given the Land of Israel, as a perfect stage for us to shine on. Upon entering the land, we started to build, to plan, to plant. To plant trees, and mainly to plant ourselves in the most compatible soil for our people, the Land of Israel. We started producing our own fruits.

Our Sages constantly likened humans to trees. King David opened his book of Psalms with the following words:

"The praises of a man are that he did not follow the counsel of the wicked... He shall be as a tree planted beside rivulets of water, which brings forth its fruit in its season, and its leaves do not wilt; and whatever he does prospers."

(Psalms 1)

Rabbi Shmuel of Sukhachev (1855-1926) gave his perspective on the reason for this comparison in general, and for our celebration of Tu B'Shvat:

"As I see, the tree is the one that connects the fruit to the land. [I]t contains the power of connection... And from the tree's physical feature, we can learn about its spiritual essence. Because of this essence, the Human is likened to the tree, as it is mentioned in the Torah: "A human is the tree of the eld" (Dvarim 20:19). The inner human trait is to link the spiritual and the physical; because humans have both the soul from the spiritual worlds, and the body, the soul's vessel, from the physical."

(Shem Mishmuel on Tu B'Shvat)

Isn't it worthy of celebration, this beautiful Tree of Life within us? It represents our ability to express our in nite goodness through actions and bring unity and oneness to a world seemingly full of negativity and separation.

But, like a real tree, this holiday also had to go through a process. Until ve hundred years ago, Tu B'Shvat was only recognized, honored and mentioned as one of the days we are not supposed to mourn on. Then, something special happened on a little mountain-top city in northern Israel named Tzfat. More and more teachers started revealing the spiritual sides of Judaism. This same group of people started celebrating Tu B'Shvat as a real holiday by eating from the fruits of the Land of Israel and sharing the wisdom garnered from them.

Today, Tu B'Shvat is celebrated as a kind of "arbor day" in Israel. Trees are planted, feasts are held and fruits of the Land of Israel are eaten. In many regions in Israel, the holiday is ushered in by the blossoming of the almond tree, with its bright white and pink flowers, as the almond tree is known to be an early bloomer.

Service Section: Psalms, Poetry & Songs, Kiddush, Motzi & Handwashing, Food Blessings, Shabbat Blessings, Commentary/Meditations 
Source: Livnot Tu B'Shvat Companion 2015