You asked for advice so I gave you the best advice that I could. You got rid of the plant which is good - I only worry about what you did with it (please tell me you are not framing your sister with it). I will again give my advice, because I feel that you are doing something that is immoral. You may choose to ignore my best advice; but I feel better knowing that I at least tried to sway you.
I am sure you have heard that two wrongs don't make a right? You have just committed a bunch of wrongs. The fact that you don't feel good about what you did to her should be a clear indication to you that what you did was wrong and you should do something about it.
Giving your 13 year old sister catnip to smoke is just wrong to begin with. Putting your sister in a situation where she could get beat up multiplies your bad decision. I have an older sister, and we haven't always gotten along - but there is NOT A SOUL that will lay a finger on her or say a disparaging word about her without having to deal with me.
Planting paraphernalia in her room and leaving voicemails is despicable. There is nothing worse than framing someone for something that they did not do. It is even worse that you are using her own bad reputation against her to erode her defense. You are going to cause a plethora of family problems which you do not have the foresight to accurately forecast the severe consequences of these actions. This will create mistrust between your mom and her (she will feel betrayed by your mother for not listening to her pleas of innocence - and your mom will lose all trust because she will see her daughter as lying straight to her face because she was caught red handed). She will never trust you or your father again (two men in her life) and this may start a life of terrible relationships with men.
You are literally doing things to her at the age of 13 that may RUIN her life!!!
I hope this is all an exaggeration or a complete fabrication. I really do. This is a bad situation that has just been made a whole lot worse by you. You need to be there for your family, not try to bury them as a form of revenge. If your mom has found pieces / heard voicemails, you must do everything to clean up the mess that you just made. You may actually garner some respect in your sisters eyes.