For three years it shall be forbidden to you; it shall not be eaten. (Leviticus 19:23)
The fruit of a tree may not be eaten in its first three years counting from when it is planted. It doesn’t matter whether one planted a seed, a shoot or a sapling – you have to count three years. The prohibition applies to the fruit and to all of its natural protections, such as shells or rinds, so long as the nature of such protective covering is to remain on the fruit and that the fruit would perish without it.
Fruit of this three-year period is called orlah, referring to its forbidden and unused nature. (“Orlah” is also the word for a foreskin, which is removed in the covenant of circumcision.)
From the Torah’s terminology, “When you enter the land and plant any tree for food…” (Leviticus 19:23), one might naturally assume that this mitzvah applies only in Israel. However, the Sages knew from a halacha l’Moshe miSinai (a law communicated verbally to Moses at Sinai) that this mitzvah applies everywhere but that one might act leniently in a case of doubt outside of Israel. (Normally, we act stringently in a case of doubt when it comes to Biblical prohibitions. See Talmud Kiddushin 38b-39a for more on this particular halacha l’Moshe miSinai.)
The reasoning underlying this mitzvah will be discussed in the next mitzvah, where we talk about what happens to the produce of the fourth year.
This mitzvah applies to both men and women at all times and in all places. It is the subject of the tractate of Mishna entitled Orlah and is discussed in the Talmud in tractate Kiddushin on pages 38a-39b. This mitzvah is codified in the Shulchan Aruch in Yoreh Deah 294. It is #192 of the 365 negative mitzvos in the Rambam’s Sefer HaMitzvos and #105 of the 194 negative mitzvos that can be fulfilled today as listed in the Sefer HaMitzvos HaKatzar of the Chofetz Chaim.