And all the trees of the field shall clap their hands.
The 15th of Shevat is the Rosh Hashanah (New Year) for trees. In our current day it is a sort of national Arbor Day for Israel that is celebrated in various ways including tree planting ceremonies to beautify the land of Israel and dontations made to the Jewish National Fund for the promotion of horicultural improvements in Israel.
Why do I bring this up, you may ask? Well, today corresponds to the 15th of Shevat on the Jewish calendar. Technically, the 15th of Shevat began yesterday (Friday, Feb. 2nd) at sundown and will end today (Saturday, Feb 3rd) at sundown. (I'll share a bit more about the Jewish day in my next post).
The Jewish calendar has more than one "New Year" which may seem weird to us western thinkers at first, but is makes a bit more sense if you think of how we have our calendar year (Jan - Dec), our school year (Aug/Sept - June) and businesses often have fiscal years that do not end in December.
Tu B'Shevat which literally means the 15th of Shevat, is the only Rosh Hashanah that occurs on the full moon. All the others begin on the new moon. (Note: Jewish months are lunar, more on this later as well). Historically this has been a day for tithing produce from fruit trees. It also traditionally marks the first day of Spring in Israel.
Here are some more links if you are interested in learning more about Tu B'Shevat
Tu B'Shevat - Judaism 101
Tu B'Shevat - Rosh Hashanah for Trees (Hebrews4Christians)
Chabad.org - Holidays (Tu B'Shevat)
OU.org - Tu B'Shevat