It takes a lot of guts to do what you did, Clint, especially at your age. You should be proud of yourself. I know it's cliché, but admitting to your problem is the biggest part of the solution; at least now you are being honest with yourself and others about what's going on. It's scary to have a problem that you can't tell others about - I've watched a lot of people waste away from trying to bear those kinds of burdens on their own. From here on out all you have to do is make the choices that you already know are right. The first thing they tell all my friends that go through addiction treatments when they're released is, "Find a hobby!" Lucky you, you've already got your plants (and us, for what it's worth!) We all know you can beat this, and we're here to help, too.
NG, it isn't exactly clear to me what's going on from the context of your message. Is your friend just using recreationally, or has it become a problem in her life? Drugs are a slippery slope; just like with alcohol, there are plenty of people who use irresponsibly for fun, and we may not like how they act when they do so, but there's not a lot that you can do to change a person just to suit your aesthetic. I'm personally pro-legalization, but I have had friends who really screwed their lives up on the stuff and I give them a hard time about using. They, beyond just acting stupid, dangerous or annoying when under the influence, turn into total flakes while using, both when high and sober, because their drugs of choice become so central to their everyday life. It's destructive, and therein lies a crucial difference.
You need to get into your friend's head a little and try to understand why she's using. Some people self-medicate, some people use for fun, and others to escape. Most people do a mix of all three. Whether her reasons are justified and responsible is a matter of your opinion, but you do need to assess the situation fairly, as her friend. If it's the case that you just don't enjoy being around her when she's high and it's not really affecting her success or wellbeing, then you should just explain to her in a nonaccusitory manner that you would prefer to spend your time with her when she's sober and that she should find other things to do when she's high. But if something serious is going on - she's using in order to ignore her responsibilities or some emotional trauma, or her habit is getting in the way of her life - then you need to confront her.
Everyone is different in the way that they respond best (or least bad) to a confrontation about how they run their life. Usually it's best to do things in an intervention-type situation, but it's not always necessary. Basically, you need to present the situation as it appears to you, and explain to your friend why her habits concern you. Try not to be angry or accusitory, and make sure to listen. Most people who have been way out of line will try to make excuses and play things off, but there are some situations where they might actually offer some insight into their situation in response to your concern, so you have to break out the ol' BS detector and pay close attention. Hopefully, your friend will be in a reasonable state of mind and you won't have to butt heads about it. However, you will need to be ready to call her on things if she starts to get out of line - that's where having other people around can help.
Finally, you need to be prepared for the worst case, which is that she is in a bad situation and you can't do anything to change it. People headed for the bottom will pull you down with them, and they'll pull hard. Sometimes the best way to be a friend is to stand aside and let nature take its course. It's not easy to watch a friend hurt themself, but the only way that they'll change their behavior is if they realize that something is wrong. Some people just don't listen to good advice; they have to find out the hard way.
NG, feel free to PM me if you'd like to discuss this in detail. Clint too, for that matter.
Rock on guys.
~Joe