Sweden has traditionally consumed foreign cannabis, which was usually smuggled in through Denmark, but in recent years the police have detected a rise in domestic illegal plantations.
"Large-scale cannabis production is definitely on the rise and is expected to grow even more," police officer Torstein Norman says.
Most of these illegal plantations are located in isolated houses in rural areas, which the producers buy cheap.
"It's very likely to be organized crime. The bigger the plantation is, the better organization it requires," says Norman.
Large-scale marijuana plantations first appeared in Sweden in the early 2000s, as online sales of seeds and cultivation equipments became common.
Most of the 800 Swedish marijuana consumers interviewed in a 2013 study by the EU said they had bought locally produced marijuana.