Did You Know...by Talmudic University
This week is Tu B'Shevat (15th of Shevat) - the Rosh Hashanah of trees. The Torah compares man to a tree of the field (Devarim 20:19); hence this day also recalls the Divine judgment upon man. This is the character of Bnei Yisroel: they rejoice on a day of judgment. Whatever the decision is, let all see that "there is a law and that there is a Judge." The Torah is the law, and Hashem is the judge.
In halacha, Tu B'Shevat is primarily a demarcation point for various tithes, specifically regarding fruits. If they blossom before the 16th of Shevat then they are considered to be produce of the previous year, and if it's after the 16th then it's part of the next year. This day is used because most of the previous year's rains have fallen, so any new growth of fruit is a result of the brachos of the new year. Interestingly, grains and vegetables have the same Rosh Hashanah as us - the 1st of Tishrei.
A common minhag on Tu B'Shevat is to eat various fruits, specifically the fruit of Eretz Yisroel (Kitzur Shulchan Aruch 139:26). Other minhagim include eating carob, having a seder of fruits, and eating esrog jelly. There is also a minhag to daven for a good esrog on Tu B'Shevat (Bnei Yissachar Shevat 2:2).
It is interesting to note that several Yomim Tovim start on the 15th of the month. Pesach, Sukkos, Tu B'Shevat, Tu B'Av, and (Shushan) Purim all occur on the 15th of their month. Maharal writes that these festivals are to teach us that when Klal Yisroel were at their zenith (much like the moon is at its zenith on the 15th day of the lunar month), they had acquired fifteen levels of holiness (as enumerated in Dayenu), the ultimate sphere of holiness as represented in Hashem's name י-ה.