Sims cannot be prompted to automatically water all live houseplants in their vicinity if those houseplants sit on elevated surfaces such as tabletops or ledges (except in the case of two or more houseplants that rest on the same surface). Unless live houseplants are sitting on the floor, the sim needs to be prompted to water them one houseplant at a time.
Edit By Crinrict: Adjusted Title to better reflect the issue
