Your worst companion planting
Mine is to grow pink jasmine on the fence, and wisteria on a post/cable structure next to the fence, and then not do adequate maintenance. Six or seven years later ... OMG I am totally eradicating the pink jasmine, it has been a much bigger hassle than the wisteria, plus it doesn't go dormant! At least the wisteria takes part of the year off and gives me time to reign it back in :-)
So what has been your worst companion planting?