Zoreah

Basics

1. In general, any action that initiates or promotes plant growth in any way is included in the prohibited Melacha called Zoreah (planting).
2. Planting of any amount is forbidden. The applications of this prohibition are planting, grafting, removal of obstacles to the plant, fertilizing, watering, spraying insecticide, putting seeds in water, and moving a plant in a bored pot.
3. Pruning a plant, removing weeds from a lawn or garden, fumigating with insecticide, or removing rocks from on top of a sprouting plant are forbidden as Zoreah (because they all promote plant growth).

Dropping seeds

1. One must be very careful not to drop or throw seeds, pits or cores of fruit or vegetables on the ground on Shabbat.
2. If one accidentally dropped a seed on Shabbat, if the seed is not muktzah (such as watermelon, apple, pear, or sunflower seeds, bird seeds) then it should be picked up right away (in order to violate Zoreah according to some opinions) and if the seed is muktzah (such as raw beans, raw peas, garden seeds, date pits, and date pits) it should not be picked up only after Shabbat.
3. Placing a seed on a well trodden path isn't a violation of Zoreah (because the seed won't sprout), however, this is inadvisable because one could misjudge the situation and many seeds are muktzeh. (for which seeds are muktzeh see last halacha).

Watering plants

1. It is forbidden to water a plant on Shabbat because of Zoreah.
2. Washing one’s hands over plants on Shabbat is forbidden because watering a plant helps it grow and is forbidden on Shabbat.
3. One should be careful not to spill any liquid or even to spit on plants on Shabbos.
4. Urinating on a plant isn't a violation of Zoreah (because the caustic fluid doesn't help the plant). See the halacha about urinating into dirt (Melachet Lash).

Removing a Sukkah covering

1. If it rained and water collected on a Sukkah covering (shlock) and by removing the covering the water will spill onto grass it is only permitted to remove the cover if the grass is fully saturated (such as after it rained steadily for a long time and the ground hasn’t begun to dry). However, if the grass isn’t fully saturated one may not remove the covering if by doing so one will spill rainwater on the grass.
2. If the Sukkah is on a pavement or deck and the water will first spill on the pavement or deck and then spill over to the lawn it is permitted to open the covering provided that one doesn’t intend to water the grass and that some of the water doesn’t spill directly onto the grass.

Potted plants

1. If one has an indoor plant one may not open the curtains in order to allow the plant to get sunlight. Similarly it’s forbidden to open a window near a plant in order to improve the ventilation for the plant. However, it is permitted to open the curtains or open a window if it is done in order to brighten or ventilate the room and the plant only benefits indirectly.
2. If is forbidden to move a potted plant onto soil or grass nor may one hang a potted plant above soil or grass.
3. Many authorities forbid handling a potted plant on Shabbat even if it doesn’t improve it’s growth, while some are lenient.
4. If a potted plant fell over one may sweep the dirt but one may not put it back into the plant pot.

Putting flowers in a vase

1. A bouquet of flower isn’t usually Muktzeh. Some authorities permit putting fully bloomed flowers in water on Shabbat, while others forbid in any event. Therefore, one should avoid putting any flowers in water on Shabbat.
2. It is permissible to remove flowers from water on Shabbat and if a fully bloomed flower was removed and it was in water from before Shabbat it is permissible to reinsert it.
3. One may not put tree branches in a vase with water on Shabbat; however, one may return them to water unless there are flowers on the branches. On Shabbat one may not add water to a vase with flowers or branches; however, on Yom Tov one may add water.
4. On Sukkot, it is permitted to put a Lulav back in water if it was in water before Yom Tov Also one may return the Lulav to a damp towel but one may not prepare this towel on Yom Tov. However, on Shabbat the Lulav is Muktzeh.