Ruling 1906
If a date tree or grapevine bears fruit twice a year, and if the combined total of the fruit reaches the niṣāb, then based on obligatory precaution, zakat is obligatory on it.
-Ayatullah Sistani, Practical Laws of Islam, Alms Tax (Zakat)
Alms Tax: Bearing Fruit Twice a Year
Practical Laws of Islam as per the teachings of Ayatullah Sistani
