Rabbi Lazer Brody:
Birkat HaIlanot ~ Blessing of the Trees
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.
... here is the blessing,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.
In Hebrew: ברוך אתה ה' אלהינו מלך העולם שלא חסר בעולמו כלום וברא בו בריות טובות ואילנות טובים להנות בהם בני אדם