The growing cannabis market generates billions of dollars in revenue each year. With legalization for medical use and growing demand, the pressure to produce cannabis translates into agricultural expansion. Across the country, cannabis agriculture is changing the landscape. Some evidence shows that outdoor cannabis cultivation takes place in ecologically sensitive areas. We know little, however, about factors that drive the location of cannabis production. Understanding these drivers can inform policy and regulation to mitigate environmental impacts.

Using data from Humboldt County in California, we estimated where new cannabis cultivation sites will likely be located and the number of plants in each site. We found that cannabis cultivation sites are most likely to exist near other cultivation sites. However, the size of a site is not influenced by neighboring cannabis sites. Similarly, a history of timber harvest increases the likelihood of outdoor cultivation, but nearby cultivation sites host fewer plants. Many typical drivers of agricultural site selection, such as slope, aspect, or distance to water, do not influence cannabis sites. While our results represent a first step toward understanding the emergence of cannabis agricultural activity, the changing legal status of cannabis may influence future expansion sites. Because of the network effects we observed, clear policies should address environmental concerns before harmful practices take root.