If she is a good friend, you might say to his mum that you hope he isn't getting into bad company.......... I wouldn't speak to the boy, that would be getting in the middle.
No, don't tell his mum and when he breaks into your house to steal things to sell in order to feed his habit you'll be able to tell yourself you did the right thing in keeping quiet.
I've decided to keep my mouth shut. He was with a couple of mates and if I tell his mother it could snowball.
I too don't want my windows putting through. Remember, kids nowadays want their own way.
Keep out of it. It’s pretty much a victimless crime.
If he want’s to kill himself in later life I am sure he knows it all and what he is doing.
Our immediate neighbours have got a real little opium den in the ‘games room ‘at the bottom of their garden.
I have spent many a euphoric evening on my patio in the summer thinking I ought to pour less Gin in my tonic whilst taking in the aromas of the flora etc around me. Sure their parents know in any-case.
I wouldn't tell his parents, but I might have just let him know that if I knew, then others would too. And walls have ears, as they say. And before long, his parents find out. Maybe he's not bothered though.
I'm going to have a word with him, pointing out the dangers of strong cannabis and I'll try not to preach to him. As I've pointed out in a previous answer, I won't be telling his mother.