This story is all to familiar to me, spouses and siblings who think it just grows on trees and so what's the problem if I help myself to a bit.
The problem is as we all know, growing takes time, effort, knowledge and money.
That electricity wheel whizzing around is never considered let alone the cost of nutes ,pots ,soil,meters,seeds,tents,lights the list goes on as we are all well aware of.
Lock it up the room where you grow, the box where you keep your stash. I am generous with my weed but there is a limit to my generosity, when the piss gets taken then the weed runs out.
If my Dad was a toker and he offered to show me how and let me use his gear to do it , I would have jumped at it.
Otherwise why no try bud for chores and get the feckless arse doing something for you.
A flogging ....? I don't think so. I would use the carrot rather than the stick...just make it unavailable and if he wants to buy crap weed let him and hope he gets a headache from it.
Trust is earned just like respect is.Once he has learned to respect you and your weed then maybe you can start to trust him, until then the shop is closed until further notice.
Do make sure you ocassionally share some of your awesome weed in a spliff just to remind him what he is missing and that your still willing to help him grow his own, the rest is up to him.