Just 7% of US Adults Grow Their Own Cannabis, Survey Finds

All but two US states that permit adult-use cannabis also allow for state residents to cultivate a number of cannabis plants at home for personal consumption. But despite this, research on home cultivation and its impacts on public health is relatively sparse.

Now, a new study published in the American Journal of Drug and Alcohol Abuse has found that rates of home cultivation are highest in states that permit recreational home cultivation, though the presence of physical cannabis retail stores showed some conflicting associations with home cultivation rates.

The researchers say that more work is still needed in order to properly evaluate the contribution of legalization to the decision to begin home cultivation. Similarly, further research should examine whether legal home cultivation supports public health objectives (such as reducing individual exposure to the illicit market) or may compromise them further through increasing the potential for underage access or diverting more plants into the illicit market.

Medical cannabis users more likely to report home cultivation

For this study, the University of Waterloo and University of Washington researchers examined data taken from the International Cannabis Policy Survey (ICPS), corresponding to the years 2019 and 2020. The ICPS is an online survey administered annually to US residents between the ages of 16 and 65. A total of 51,503 responses to the ICPS across both waves were included in this analysis.

Using records from the National Conference of State Legislatures, ProCon, and individual states regulatory documents, the researchers categorized each US state’s cannabis policies by the legality of cannabis use and of home cultivation. The presence of any state limits on the number of plants that could be cultivated at home was also noted, as was the presence of brick-and-mortar retail stores in that state.

Collectively 6.8% and 7.3% of US adults surveyed reported home cultivation in 2019 and 2020, respectively. On the state level, respondents in states with legal adult-use cannabis and legal home cultivation had the highest odds of reporting home cultivation in the past 12 months.

Within states with legalized adult-use home cultivation, the reported median number of plants grown ranged between 2.3 and 5.2 in 2020, depending on the state. Michigan and Maine had the highest number of plants grown.

At the individual level, people were more likely to report home cultivation within the past 12 months if they were cannabis users, lived more than 30 minutes from a retail store, or had a medical cannabis recommendation. Men, people aged 50 and younger, those with less than high school education, those who identified their ethnicity as Hispanic, American Indian, or Alaskan Native, and those who found it difficult to make ends meet were also more likely to report home cultivation than their peers.

Presence of cannabis retail stores may not affect home cultivation

In 2020, 91% of respondents in states with physical retail stores reported cultivating cannabis at home, compared to 6.8% in states without retail stores.

When examining the relationship between retail outlets and home cultivation in more detail, the researchers found some seemingly conflicting trends. Residents in states with “older” retail markets generally reported lower rates of home cultivation, but the presence of retail stores did not appear to be significantly associated with home cultivation.

“The lack of association between the presence of adult-use retail stores and growing cannabis plants suggests the policy alone is not the only factor in deciding to self-supply through home cultivation,” the study authors wrote. “It may be that stores with legal cannabis are perceived to be inaccessible or expensive, or do not stock preferred products.”

In addition to the length of time a retail market has been open, the perceived time taken to get to the nearest cannabis retail store was associated with home cultivation. Individuals who lived more than 30 minutes away from their closest retail store were more likely to report home cultivation than those who lived close by.

While it was not explored directly in this study, the researchers suggest that online cannabis sales and the presence of home delivery services may also affect an individual’s decision to begin home cultivation, and so these factors may want to be examined in future studies.

Home cultivation and public health

Based on current scientific literature, there is no agreed consensus on whether home cultivation policies are a net good for public health.

Allowing individuals to grow cannabis at home for their own personal use may help to prevent individuals from making contact with the illicit market in search of cannabis or a specific preferred strain. Conversely, there is a concern that allowing home cultivation may make it easier for underaged youth to access the drug. There is also a chance that more product may be diverted to the illicit market.

As seen in this latest study, home cultivators residing in states with cultivation limits on the number of plants that can be grown do generally abide by these limits. However, there were also a number of study respondents who reported not using cannabis themselves, but who do participate in home cultivation. These individuals may simply be caregivers for somebody with a medical recommendation, or they may be diverting cannabis into the illicit market.

“The contribution of legalization in the decision to participate in home cultivation requires further research, potentially through pre- and post-legalization studies in individual states, replicated across multiple states,” the study authors concluded.

“Future research should examine how home cultivation relates to public health measures across states with adult-use cannabis laws, including whether home cultivation supports public health measures (e.g., through reductions in the illicit market, access to specific medical products) or opposes them (e.g., through increased underage access, issues with contaminated products, or diversion to the illicit market).”