The World Federation One Stop Fiqh

Ruling 1905

If a person owns wheat, barley, dates, or grapes in various towns which have harvesting times that differ, and if the crops or fruits are not acquired simultaneously but are nevertheless considered to be the produce of one year, then in the event that the first thing to ripen reaches the niṣāb, he must give zakat on it when it ripens and on the rest whenever they are acquired. However, if what ripens first does not reach the niṣāb, he must wait until the rest ripens; if the combined produce reaches the niṣāb, zakat is obligatory on it, and if it does not reach the niṣāb, zakat is not obligatory on it.