Jewish Law
Daily Halacha: Vase of Flowers on Shabbat? Here's What You Should Know
A clear look at what Jewish law says about placing myrtle branches and flowers in water on Shabbat, based on Rabbi Ovadia Yosef

Is it allowed to place cut myrtle branches in a vase with water?
Yes. On Shabbat, it is permitted to place aromatic branches like myrtle or fragrant woods into a vase with water, even from the start of Shabbat. It is also allowed to first add water to an empty vase and then place the aromatic branches inside. Even more so, it is permitted to add water to a vase that already contains these types of plants.
However, the halacha is different when it comes to flowers like roses whose buds are still closed and likely to open when placed in water. On Shabbat, one should not initially place these types of flowers into a vase with water. And if someone takes them out of the water in order to smell them, they should not be returned to the vase afterward.
But if the roses or flowers have already opened before Shabbat, then it is permitted to place them in water on Shabbat. Someone who wishes to be extra careful and refrains from placing even already-opened roses into water on Shabbat will be blessed.
(Based on Yechaveh Da’at)
Ach Tov VaChesed – Daily Halacha