There is a worthwhile practice that many people follow to store the Arba Minim (four species) in either a moist towel or a vase to keep them fresh during Sukkot. Halacha allows placing the four species in water even on Yom Tob. It is permissible to place the Arba Minim in a vase with water on Yom Tob for the first time, as well as to return the Arba Minim to a vase in which they had been previously. One may not, however, change the water on Yom Tob. The Sages forbade changing the water because of the exertion entailed. It is thus forbidden to remove the water from a vase and place new water in the vase. As mentioned, however, it is entirely permissible to place the Arba Species in a vase if it already contains water.
Halacha is more lenient with regard to carrying in a public domain on Yom Tob than on Shabbat, and one may carry in a public domain on Yom Tob provided that this is necessary for some purpose related to Yom Tob. It would thus appear, at first glance, that one may not bring his Arba Minim home from the synagogue on Yom Tob unless he needs them at home for some purpose. For example, he might want to bring them home so his wife can fulfill the Misva of Arba Minim. (Women are allowed to shake the Arba Minim if they wish, though they do not recite a Beracha.) Or, he might want to take them home to place them in a vase so they remain fresh. Otherwise, however, we might think that one may not take his Arba Minim home from the synagogue on Yom Tob, since carrying is permitted only when this is necessary to serve a particular purpose.
In truth, however, Halacha allows bringing one’s Arba Minim home from the synagogue even if this is unnecessary. The Sages were concerned that if people were not allowed to bring home their Arba Minim, they would not bring them to the synagogue at all, out of concern that they might be misplaced or stolen. It is therefore permissible to bring one’s four species home from the synagogue, even if this does not serve any particular need.
Rav Haim Palachi (Turkey, 1788-1869) records a custom to give one’s Etrog to a pregnant woman on Hoshana Rabba, after he has used it for the Misva for the final time. The woman then bites the Pitom (stem) off the Etrog, and this has the ability to help alleviate the hardships of childbirth. Of course, not all Etrogim grow with a Pitom at the end, but if one has an Etrog with a Pitom, it would be worthwhile after using the Etrog on the last day of Sukkot to give it to a pregnant woman. Rav Haim Palachi also records the text of a special prayer that the woman should recite after biting off the Pitom, asking God to grant her an easy delivery.
Summary: It is permissible to place the Arba Minim in water on Yom Tob, though one may not change the water in the vase on Yom Tob. It is permissible to bring one’s Arba Minim home from the synagogue on Yom Tob, even in a place without an Erub. There is a custom to give the Etrog to a pregnant woman after using it for the last time on Sukkot, and she bites the Pitom off the Etrog, as a Segula ("charm") for an easy delivery.
