The fruit of a tree or fruit bush may not be eaten during the first three years of its growth. Not only is it prohibited to eat the fruit but no benefit whatsoever may be derived from the fruit. This halocha applies both in Eretz Yisroel and in חו”ל (outside of Eretz Yisroel). There is one major difference between Eretz Yisroel and חו”ל (outside of Eretz Yisroel) – in Eretz Yisroel we must determine that the fruit is not “Orla” before eating it, while in חו”ל (outside of Eretz Yisroel) we may go after the majority of fruit which grew after the first three years. If you pick your own fruit you must ascertain that the tree has been growing for at least three years even outside of Eretz Yisroel.
If a tree is replanted without a ball of earth around the roots (bare roots) the three years must be counted over again. This is how most commercial orchards plant trees. A nursery plants the saplings and when they reach the desired size they are chilled so that they go into dormancy. The young tree is shipped bare rooted as it is much less expensive to ship it without a ball of earth around the roots. This means that in most cases the three years need to be counted from the replanting, not the original planting.
The produce of the fourth year is called “revai”. It is sanctified and must be eaten in Yerushalyim. It is possible to transfer the sanctity onto coins, as is done with מעשר שני (The Second Tithe). May Moshiach come soon and may we fulfill all of the מצוות (precepts) attached to the Land of Israel, thereby meriting the Land’s Blessings in full.