Our Sages have designated the 15th of Shvat - Tu B'Shvat- as the boundary between one year and another, since (in most years) most of the rain of the winter has already fallen by then.
Any new growth of fruit after this day, is the result of the blessing of the new year.
It is customary to pray for a beautiful Kosher Etrog on Tu B'Shvat.
Source: The Book of our Heritage, Vol I, page 346-349
Wednesday, 15 Shvat 5771
Wednesday, February 8, 2012
Posted by Danny Schoemann at Wednesday, February 08, 2012