TU BISHBAT, understanding why you need a new year for trees

TU BISHBAT is the “new year for the trees”.  This is a legal technical concept, which has implications for Mitsvot related to agriculture.  The Mitsvot related to the land are called, “Mitsvot hateluyot ba-arets”, “commandments affected to the land”…of Israel, for example: teruma, maaser, shebi’it.
TU BISHBAT is essential to determine, for example, ma’aser sheni, the annual tithe.
We have different types of ma’aser. First, ma’aser rishon, a tenth of the produce which was given to the Leviim. Now, on the 1st, 2nd, 4th and 5th years of the seven years cycle ma’aser Sheni is separated, which used to be taken to Jerusalem and today is redeemed with a coin.  In the 3rd and 6th years, we give Maaser Ani (the poor tithe), which today is substituted. TU BISHBAT is the cut-off date for determining to which year the tithes belong.
Another practical example for the application of TU BISHBAT is the commandment of ‘orla, the biblical prohibition, recorded in Leviticus 19:23, of eating the fruit of trees produced during the first three years after the tree is planted.
TU BISHBAT is also the cut-off to determine the end of these three years.
Illustration: TU BISHBAT is the cut-off for trees, not for vegetables. What determines the years of vegetables is the 1st of Tishri (Rosh haShana). Now,  a fruit tree that was planted, for example, before the 15th of Ab of last year (before August 11th 2014) in Rosh haShana (Sept 25, 2014) became one year old. Why in Rosh haShana? Because this incipient tree is still considered a “sapling”, almost a vegetable, whose cut-off is the 1st of Tishri.  After three Rosh haShanas have passed the plant is no longer considered anymore a “sapling”. And since it is already a tree and not a sapling, even though three Rosh HaShana have passed, you cannot eat from its fruits until the new year for the trees arrives, i.e., TU BISHBAT. In other words, trees have their own Rosh HaShana (in the sense if their cut-off) and the prohibition of  ‘orla is NOT over until TU BISHBAT after three 1st of Tishri have passed.
Why TU BISHBAT was established as the new year for the trees?  As our rabbis has explained, most of the year’s rains have already fallen and the trees have absorbed the precipitation and now they are exuding resin, with new vitality.
One more interesting thing. Unlike the other agricultural commandments we mentioned, ‘orla applies also outside Israel.   Although the Tora indicates that ‘orla is applicable only in the land of Israel ( Leviticus 19:23 says “When you enter the land and plant any kind of fruit tree, regard its fruit as forbidden. For three years you are to consider it forbidden [b]; it must not be eaten.”. our rabbis explained that ‘orla applies to the trees planted outside Israel as well (Shulhan ‘arukh, YD, 294:8).