Can one place a bouquet of flowers in water on shabbos if 95% of the flowers are open and only 2 or 3 little flowers are closed?
(The vase was filled with water before shabbos)
Thank you for your question.
If the bouquet has flowers that will open from the water, it is similar to zoraiya, and we don’t do it on Shabbos. This would apply even if most of the flowers are already open. If only some of the flowers are opened then the opened ones may be placed in the vase, however you should be careful regarding borer not to remove the closed, bad flowers from the good ones, but the good ones from the closed ones.
As a side point, it is controversial if the open ones may be placed in the water on Shabbos. Therefore, one should preferably make sure to place them in the water before Shabbos. If you forgot, then if all the flowers are open, it may be placed in the water.
Rema 336-11, M:B 336-53, Shar Hatzion 336-48.