In my current save, in Moonlight Falls, my PlantSim had an enemy. I decided she should pull a prank (My household has 4 Females and 4 Males with no room for babies ) on said enemy with the Poison Kiss. I didn't see the interaction because someone else was doing something stupid, so I did it a second time and then threw a Potent Jar of Friendship at them. Then a little while later, they wanted to chat or something with ANOTHER PlantSim, but I knew no one on my property at one moment was another PlantSim. I checked the relationship panel and what did I find, that the victim of the Poison Kiss became a PlantSim too!
Now I am testing it on one of my sims (Female, all my males are occult) to see if it turns others into PlantSims, then I'll spread the garden to take over the world! Hoo haa haa haa! JK, just a little joke because that's what the vampires try to do in Late Night. Has anyone else seen this? Tell me more about it, no where on the internet that has good The Sims 3 info goes into depth with PlantSims.

After the 3H Poisoned Moodlet wears off, the target of the kiss becomes a PlantSim with the same skin tone at the head, hands, and feet as the original PlantSim who spread it! If you want an easy PlantSim family then, gain the Social Networking skill, make two sims enemies with one being a PlantSim, then spread the PlantSimnism to whoever and raise PlantBabies to make a never ending family of plants! If anyone wants to join me on the quest for PlantSim information, come to The Toadstool for a chat. Edit: The kiss adds Botanitis Minorous for possibly a shortened time randomly during the Poisoned moodlet that ends near to the end of said Poisoned moodlet.

Necro'ing the thread to add that I just read that if you poison kiss a non occult enemy ( a human ), there is a 15% chance that they may become a plantsim after the 3 Hour poisoned buff wears off.