What plants are you considering?
Have you looked at the Deadly Plants thread?
I'll be interested to see if anyone comments that they've tried toxic plants.
Don't be surprised if you get a lot of NO responses here discouraging you from trying. It's one of the least popular methods on the forum, after suicide by cop, cars and trains. But those are methods that force others to participate. I think if you are able to get enough data for the plant method to know what to expect and you feel confident in your decision, it's your call.