Verified answer

15 Shevat (Late January/Early Feburary). New year of the trees.

Even Google is programmed to answer that question.

https://www.google.com/search?q=when+is+tu+bishvat...

Also see https://www.hebcal.com/holidays/tu-bishvat

The 15th day of the Hebrew month of Shevat begins after sundown on January 20 and ends at sundown on January 21, 2019

It begins on the evening of the 20th of this month, and ends on the evening of the 21st.

http://lmgtfy.com/?q=What+the+date+on+the+secular+...

It starts at local sundown this Sunday, 20 January.