Home cultivation across Canadian provinces after cannabis legalization.

Aims: Little research exists on home cultivation in Canada after non-medical cannabis legalization in 2018. The aims of the study were to: (1) estimate the percentage of home cultivation before and after legalization; (2) estimate the quantity and expenditure of cannabis plants; and (3) examine the association between provincial policies and home cultivation after legalization. Methods: Repeat cross-sectional survey data come from Canadian respondents in the International Cannabis Policy Study in 2018, 2019, and 2020. Respondents aged 16-65 were recruited through online commercial panels. Home cultivation rates were estimated among all respondents in 2019 and 2020 (n = 26,304) and among a sub-sample of past 12-month cannabis consumers in 2018-2020 (n = 12,493). Weighted multivariable logistic regression models examined the association between home cultivation and provincial policies among all respondents, 2019-2020. Results: Cannabis consumers in 2019 (7.9%; AOR = 1.47, 95% CI: 1.07,2.01) and 2020 (8.8%; AOR = 1.62, 95 %CI: 1.18,2.23) had higher odds of reporting home cultivation in the past 12 months than pre-legalization (5.8%). Post-legalization, past 12-month home cultivation was lower in Quebec and Manitoba, the two provinces that prohibited home cultivation (3.2%), than in provinces where home cultivation was permitted (6.8%; AOR = 0.48, 95 %CI: 0.39, 0.59). The median number of plants grown across all provinces was between 3.1 and 3.5 in all years. Conclusions: Almost one in ten Canadian cannabis consumers reported home cultivation of cannabis in 2020, with modest increases following legalization and most growing within the non-medical limit of four plants. Home cultivation was less common in provinces where home cultivation was prohibited.