Tu bi-Shevat is the New Year of the Trees. In practical terms, it is the cut-off point that the rabbis set to determine if fruit and nuts counted toward the current or past year's tribute. But spiritually, modern celebrations combine Kabbalistic thought with environmental activism. Check the library catalog for many examples of Tu bi-Shevat seders, prayers, and activities. See our research guide for more tips and links.
The "Tu" in Tu bi-Shevat represents the number 15, the holiday is celebrated on the 15th of the month of Shevat. This usually corresponds to the end of January.