Placing flowers and plants into water on Shabbos:
Branches [and flowers] which have been designated before Shabbos for a specific use in a way that they are no longer considered Muktzah, may be entered into a bucket or vase of water on Shabbos, if the water was placed into the vase or bucket from before Shabbos. It is however forbidden to place water in a vase or bucket on Shabbos [or Yom Tov] for the purpose of placing the branch in it. Furthermore, if the branch contains flowers [which are not fully open] or buds it is forbidden to place them in water at all on Shabbos being that the moisture of the water causes the flowers to further open.
Adding water to the vase: In all cases it is forbidden to add water to the vase on Shabbos. However on Yom Tov it is permitted to add more water to the vase [if the plants do not contain flowers or pellets]. [Some Poskim however limit this allowance to add water on Yom Tov to only up until half of the current amount of water found in the vase. It is however forbidden even on Yom Tov to add more water than the vase originally contained.]
Switching the waters: It is forbidden to switch the waters of the vase/bucket in all cases, whether Shabbos or Yom Tov.
- Example-Placing flowers into a water vase: Flowers which were designated to beautify the home, such as flowers bought for Shabbos, are not Muktzah and may be entered into water on Shabbos if the water was prepared from before Shabbos, and the flowers will not further open due to the water.
- May one water his Lulav/Hadassim/Aravos on Yom Tov?
One may enter them into a vase with water, if the water was placed into the vase before Yom Tov. One may likewise add more water to the vase [if the amount will not exceed the original amount of water in the vase].
It is only permitted to enter plants and flowers into water on Shabbos if:
- The plant has been designated before Shabbos for a use such as to beautify the home, and is thus not Muktzah.
- The plant does not contain flowers or pestles which will further open in the water.
- The water had been placed in the bucket or vase from before Shabbos.
May one sprinkle water onto detached flowers and plants?
This matter requires further analyses.
May one move the flowers towards the sun in order that they open?
May one remove plants from the water on Shabbos?
Yes. This applies even to flowers. If however the plant stayed in the water long enough that it has begun rooting, then it is forbidden.
May one make a flower bouquet on Shabbos?
 Being that the designation has given them a status of a vessel. [ibid]
 Meaning not only may they be returned to a vase if they were removed from it on Shabbos, but one may even initially place the plant into the vase on Shabbos for the first time if it contained water from before Shabbos. [so is understood from Admur ibid, and so understands M”B (336/54 in Shaareiy Tziyon 48) to be the opinion of Admur, and so understands also Kaf Hachaim 336/75 to be the opinion of Admur. As rules Admur so rules also Peri Megadim A”A 336/13; Bechureiy Yaakov 654/2; and so leans the M”B in Shaareiy Tziyon to be lenient]
Other Opinions: Other Poskim [first opinion in M”B 336/54 in name of Chayeh Adam 11/3; Tosefes Shabbos 336/21; Kapos Temarim brought in Kaf Hachaim 336/75; 654/4 and so rules Kaf Hachaim himself] rule it is forbidden to place the branch into the vase for the first time on Shabbos and only if it was removed from the water on Shabbos may it be returned to it. Regarding placing the plant for the first time on Yom Tov it is allowed to be done as even the above Poskim were only stringent regarding Shabbos. [So rules Kaf Hachaim 654/4 and Kapos Temarim ibid]
 So is implied from Admur ibid that it has to be placed before Shabbos and so rules M”B 336/54 explicitly.
 Bechureiy Yaakov 654/2; Kaf Hachaim 336/79; In 336/18 Admur does not explicitly mention Yom Tov, although he also does not differentiate in this aspect.
 So is implied from Admur as stated above and so rules Kaf Hachaim 336/79. The reason for this is because one is troubling himself to “fix” the plant and it is thus similar to the prohibition of switching waters.
 If however the flowers are already fully open, there is no prohibition to place them into water, as explained above.
Other Poskim: Some Poskim rule it is permitted to place roses and other flowers into the water as even if they open it is merely revealing that which was already concealed and only by grains and the like which actually root in water was it forbidden. [Kaf Hachaim 336/77]
 As it is forbidden to trouble oneself to fix a vessel. [ibid] Meaning watering the plants is like he is trying to fix them.
In Admur here he records, “and Yom Tov” regarding the prohibition of adding water to the vase. However in Lekutei Sichos 21 p. 385 the Rebbe notes that it is a printing error and really it should read “and change the water on Yom Tov”. However to add water is permitted on Yom Tov as is explained in 654/1
 Aruch Hashulchan 654/2
 As this switching of water involves a greater trouble than simply adding water, and is hence forbidden to be done even on Yom Tov. [Kaf Hachaim 654/4 in name of Peri Megadim]
 Aruch Hashulchan 654/2
 On the one hand it is forbidden to initially place water into a vase due to Tikkun Mana, and hence here too it should seemingly be forbidden. On the other hand perhaps it only applies when placing water into a vase being it is a greater trouble than simply sprinkling it. To note that SSH”K 26 footnote 97 allows dripping water onto the Lulav and dry cloth in order to wet it, hence implying such a matter has no prohibition of Tikkun Maneh.
 Piskeiy Teshuvos 336/11
 Igros Moshe 4/73
 This is forbidden due to fixing a vessel, as the gathering of the different flowers to make a bouquet are considered making a nice vessel out of the flowers. [ibid] However see Ketzos Hashulchan 8 p. 92 which seems to imply that the only question involved in gathering the flowers together is the prohibition of Miameir. However when done outside of the area of growth, such as in one’s home, it is permitted. Hence implying doing so does not carry the Tikkun Keli prohibition. Furthermore it requires further analysis on the essence of the logic to consider simply placing flowers near each other as Tikkun Keli. It does not appear at all like one is making a Keli. This is unlike a necklace which when one enters the beads it is clearly apparent as if one is making a Keli. Vetzaruch Iyun.