['Cannabis markets are often described as less violent than other drug markets. Domestic cannabis cultivation markets seem to be especially non-violent. However, few studies have investigated why this might be.', 'Two and half years of ethnographic fieldwork among indoor cannabis growers and interviews and conversations with 52 growers in Norway.', "This study identified four barriers and a set of values that prevent violence among growers. (1) Violence attracts increased attention from police and enemies, which inhibits 'business as usual' and reduces profits. (2) Careful attention to profits makes growers calculate and prepare for financial losses. (3) The prospect of covering debt by producing more cannabis makes it possible to choose non-violent sanctions. (4) Tight social ties and friendships prevent violence when conflicts erupt. However, the cannabis culture of the actors and the transactions stands out as the main reason why these four barriers are more important in cannabis markets than in other drug markets."] Do four barriers and a set of values that prevent violence among cannabis growers?