# In general, any action that initiates or promotes plant growth in any way is included in the prohibited Melacha called Zoreah (planting). <ref> 39 Melachos (Rabbi Ribiat, vol 2, pg 261) </ref>
# 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. <Ref> Rambam Shabbat 8:2, Eglei Tal Zoreya 1,4-8 </ref>
# One must be very careful not to drop or throw seeds, pits or cores of fruit or vegetables on the ground on Shabbat. <ref> 39 Melachos (Rabbi Ribiat, vol 2, pg 264) </ref>
# One should be careful not to spill any liquid or even to spit on plants on Shabbos. <ref> 39 Melachos (Rabbi Ribiat, vol 2, pg 267-8) </ref>
# Urinating on a plant isn't a violation of Zoreah (because the caustic fluid doesn't help the plant). <ref>S"A 336:3, Mishna Brurah 336:28, 39 Melachos (Rabbi Ribiat, vol 2, pg 267-8) </ref>See the halacha about urinating into dirt (Melachet Lash).
==Putting flowers in a vase==
# 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. <Ref>S”A 654:1, Mishna Brurah 336:54, Shemirat Shabbat KeHilchata 26:26 </ref>