When I was in South Korea, I was acquainted with a Dutch individual who worked as a teacher at the Dutch embassy. This individual had an interesting operation in his Itaewon apartment: he had some 40 plants growing and ready to supply his people. Eventually he was caught, and the South Korean government was not at all too pleased, to say the least.
The South, fortunately, has a mild punitive system compared to the North's brutal gulags, but it is not easy to predict exactly how the North would react if they found a plantation in a foreigner's house. We can't predict simply because there are too few foreigners living in North Korea, but it seems like they don't do much to the locals.
High cannabis use seems to be one of the North's best kept secrets. North Koreans are very well aware of the negative perception that East Asians and many around the world harbor against the plant, and are always very careful to suppress outside knowledge of the country's rampant love for the crop.
Cannabis is generally seen as a cheaper substitute to the already massively cheap North Korean cigarettes. Citizens reportedly use copies of the Rodong Sinmun, the state newspaper, to roll joints. I had long suspected that cannabis use was a very high possibility in the North, considering the high use of meth and the harsh penalties handed out for its use. I believed that the government would also likewise oppress all cannabis users, but travelers to the North have reported entire roads lined with cannabis plants.
However, don't start packing your lighter and President Kim Il-Sung pin just yet. The North won't let anyone travel without a guide and a minder, so you won't likely get to see what life is really like for the average North Korean. Though repressed in almost every way, the people in The Democratic People's Republic of Korea have one freedom that their South Korean counterparts don't have: the freedom light up a spliff after a very relaxing 16 hours at the Socialist Utopia Reeducation Center.
The two countries do seem to have one thing in common, however: most pharmacist will just give you whatever you want if you ask for it in English. A friend who traveled to Pyeongyang reported that he was able to get a very nice dose of morphine just by asking for it at the pharmacy. A perplexed woman at the counter simply bowed her head and handed over whatever he politely asked for while saying, "doctor in Canada give."