Once a year, during the Hebrew month of Nissan, we have the special mitzva of making a blessing over (at least two) blossoming fruit trees. According to Kabbala, this blessing is deeply significant, and helps correct the soul that is reincarnated within the tree. That soul is forever beholding to the person that makes the blessing, for he or she has done a great favor in helping that soul attain its tikkun, or correction.
ברוך אתה ה' אלהינו מלך העולם שלא חסר בעולמו כלום וברא בו בריות טובות ואילנות טובים
להנות בהם בני אדם
In English: Blessed are You, Hashem our God, King of the Universe, who let nothing lack in His universe and created within it good creatures and good trees in order to give pleasure to human beings.
In Transliteration: Baruch ata Adonoi, Eloheinu Melech ha-olam, she-lo chisar be-olamo klum v-vara vo beriyyot tovot ve-ilanot tovim lehanot bahem bnai Adam
Women should also recite the Blessing of the Trees in the month of Nissan and although they are exempt from other time-bound Mitzvot based on Sefer Turei Evven (Megillah 20b) that says that women too are commanded to bring Bikurim to the Bet HaMikdash…
When the spring (Aviv) season arrives, a blessing is traditionally said when one is in view of at least two flowering fruit trees. In the northern hemisphere, it can be said anytime through the end of the month of Nissan (though it can still be said in Iyar). For those who live in the southern hemisphere, the blessing can be said during the month of Tishrei (and into the month of MarḤeshvan)
Rabbi David Seidenberg writes:
The language of the blessing recalls part of the borei n’fashot blessing for food, which thanks God for creating “many souls and all their deficiencies”ḥesronan, yet here we say that there is nothing missing or lacking. One could say that the things we lack are themselves the essence of creation, calling us to weave relationships with all forms of life. The gift of fruit, however, embodies an even greater sense of pure abundance and blessing than almost anything else we encounter.
We have a unique intimacy with fruit trees. In scripture that goes back to Gan Eden and the tree of knowing. The connection is even more powerful in the midrashic interpretation of the statement in Deuteronomy 20, Ha’adam eitz ha-sadeh, “A person is a tree of the field” (that is, a fruit tree). (The statement in context is really a question.) For the Kabbalah, a fruit tree is as true an image of God as a person (see below as well as the blessing from P’ri Eitz Hadar). The Sefirot, “the Tree of Life”, are thought of as a fruit tree. The reason why is that a fruit tree embodies the principle of sharing, and is a more perfect model for how God interacts with the world than human beings can be.
Why do we need to see two trees rather than just one to say the blessing? I haven’t heard an explanation, but one reason is that the trees need each other to reproduce, at least on the species level (most fruits—except dates and a few others that are gendered by tree—can also fertilize themselves). The halakhah (religious rules) specifically forbids saying the blessing over trees that are grafted from one species onto another – there is an idea of appreciating the awesome reality of this world in itself, separate from human ḥokhmas (wisdom) and power.
Quotes about fruit trees from Tanakh, midrash and Kabbalah:
The Ba’al HaBait told me his father had the same tradition, it’s been a tradition in the family for 90 years to have this gathering on the first day of Ḥol HaMoed. When they built the house they planted the fruit trees before starting to build so that they would be able to have this gathering for the community.
Rabbi Yosef Israel told me that in Tetouan when he was growing up it was a tradition to go to someone’s house that overlooked the whole city of Tetouan and spend the first day of Ḥol HaMoed in the garden and gathering as a community. In Portugal the community in Belmonte goes out for a picnic during the days of Ḥol HaMoed as well. Ḥag HaAviv–Passover is also called the Spring Holiday–beginning to enjoy the trees, the sun and the outdoors.