If Joe can grow weed in his cupboard, he absolutely can grow poppies and produce opium. The process is not complex.

The required acreage to yield opium in significant quantities is way beyond a closet (or even a basement). Not to mention that heroin is ~1% of total opium weight.

If we're talking about Joe's personal use, a single poppy plant produces multiple doses, according to this[1] reference and some anecdotal drug forum dose suggestions, on the order of tens of mg.

1.https://erowid.org/archive/rhodium/chemistry/opium.html

>produces multiple doses

Could you tell me what number "multiple" is and what a "dose" looks like?

Are we talking about raw plant material that is opium, or refined heroin/morphine/codeine? The conflation of the word drugs and plant material seems like the most absurd gorilla in the room.

Off to do some coffee...

welcome to our grim cyberpunk (near-)future: https://www.wired.com/2015/08/dont-try-home-scientists-brew-...