Question: What is the law of saplings?

Answer (Beraisa): One who plants, sinks or grafts 30 days before Rosh Hashanah (of Sheviis), (meaning that it can be considered to have been planted a full year before Sheviis) may leave it growing in Sheviis; otherwise, he must uproot it. However, they said that the fruits of this sapling are prohibited until the 15th of Shevat.

Question: What is the reason? R. Yasa quoted R. Yochanan as saying - the Pasuk states (Vayikra 19, 24), "and in the 4th year''.

R. Zeira: The Pasuk states (Vayikra 19, 23), "For three years they will be prohibited to you, they shall not be eaten. In the [4th] year...'' - in certain cases, it will be prohibited even in the 4th year, namely, when it was planted within 30 days of Rosh Hashanah.

R. Ba bar Mamal to R. Zeira: The law (that fruits of the 4th year are prohibited until the 15th of Shevat) appears correct in a case when it was planted 30 days before Rosh Hashanah (as the 1st year is be considered a year and when the 4th year arrives, he has not yet waited 3 full years) but less than that (meaning that the 1st year cannot be counted, when R''H of the 4th year arrives, more than 3 full years have passed since it was planted)...

Conclusion of question: If he has already finished counting 3 complete years, how could you say that he must also be prohibited in the 4th year?

R. Zeira responds: If that is the reason to add a 4th year, the 4th year should only be prohibited until 30 days before R''H?

Question: So what is the reason?

R. Mana: Since when R''H arrives, he is in the middle of a year of the tree's growth, he should complete that year.