Tu B’shvat is the Rosh Hashanah for trees, and is a special day for Klal Yisroel. We eat Hashem’s delicious fruits, and thank Him by making a Bracha with Kavana. Why do we make such a big Shpeil about fruits?
Fruits are so important in our lives, because they symbolize productivity. The Avos were always building Mizbeach’s, to symbolize their mission in life; i.e. to build and to grow and become great. Having children was always on their mind, to show the importance of the ideal produce, P'ru uR'vu; don’t just stagnate and live for yourself, bring more people into this beautiful world to serve Hashem!
This is why the Chovos Halvavos says that Zikkui HaRabbim is more important than the highest Madregos like Nevua. That’s why fruits are so delicious and sweet, to symbolize how important and beautiful is a person’s growth; his having children, his writing a Sefer, his learning Torah, and his Zikkui HaRabbim. Fruits are also colorful, with loads of variety. This shows the beauty and uniqueness of every individual in Hashem’s world.
Trees are facing Shamayim, and only fruits are what Tu B'shvat is all about (not vegetables), since the main productivity of a person is Ruchaniyus i.e., Torah and Mitzvos, and not: אַ רְ צִ יוּת earthliness (like to produce improvements and inventions to enhance our stay in Olam HaZeh) unless it’s L'shem Shamayim. That’s why vegetables aren’t sweet, although they also have importance. The Maharal says that a Mitzva has to be beautiful, since Ruchaniyus has to be beautiful and sweet.
Remember how a mere tiny seed turns into a hard-tall tree, and eventually into those sweet delicious fruits that Hashem made. Respect yourself; how you were once disadvantaged in some way or other, and with Hashem’s help you overcame and became a Talmid Chochom or Baal Chesed, or any other accomplishment in Ruchaniyus that once didn’t seem likely; but with your Tefilos and your sweet memories of K'riyas Yam Suf you had Bitachon and didn’t give up davening - until - אַ שְ ר יכֶם!
אָ שִׁ ירֵָה and: אָ ז יָשִ יר are both in future tense, as a Remez to keep singing and singing for the rest of your life (like Zemiros on Shabbos and P'sukei D'zimra, etc.). Remember! The more ugly and smelly fertilizer, the more beautiful the tree and its fruits. Your difficulties in Avodas Hashem and your rotten past makes you Davka superior to others!
