Just remember, your cow plant is part of your family. You have to feed it, (a lot), pet it, and play with it. If I just feed it, it gets hungry faster, so I treat mine like a child. I feed, pet and play several times in the day with both my adult Sims. There is no interaction with children. Since I have a gardener Sim she is in the area where the cow plant is anyway so it's no biggie.