International Cannabis Cultivation Survey

March 2021


In the current research environment, category one grant success is strived for and appropriately lauded when won. In contrast, there is little recognition of largely unfunded research collaborations that exist because of a shared commitment to conduct research that is unlikely to be funded by government or competitive funding bodies. The research described here is one such project, which is largely unfunded apart from the in-kind contributions of the research staff and their respective organisations. It is enjoyable to be a part of because: the focus on the content and discovery of new knowledge with policy relevance; and it involves smart collaborators who enjoy working together and supporting early career researchers who share an interest in cannabis policy and cultivation research. As we are currently surveying cannabis users (growers can access the survey at in phase two of this research, in which we have surveys completed by more than 6,000 growers in some 50 countries thus far, it’s timely to review this unique project.

As context, since the mid-1980s there has been a decline in cross country supply of cannabis and an increase in cannabis production within consumer countries (domestic production) by outdoor and then indoor cultivation. This was increasingly undertaken by small-scale growers growing for themselves and their peer group, using technical knowledge available, initially from magazines and more recently via online sites and forums. However, most research on cannabis growing had been based on criminal justice data on large criminal organisations, which did not capture the experience of these small-scale growers (1).

Evolution of international, collaborative research on cannabis cultivation

In 2006-7, Tom Decorte, Professor of Criminology at The University of Gent in Belgium, conducted a web survey with 659 Belgium cannabis growers (2), which was replicated by researchers in Finland and Denmark (3). In 2009, Tom contacted a group of cannabis researchers internationally, including Lenton here at NDRI, to contribute to a book on academic research on cannabis cultivation (4) and to consider conducting some further transnational research.

In 2011, the Global Cannabis Cultivation Research Consortium (GCCRC) was born and we set up a website with a URL ( hosted in the Netherlands, mindful of the cache that comes with the history of cannabis policy in Amsterdam and elsewhere in the Netherlands. Initially comprising 12 academic members, in 2012-13 we conducted our first survey of 6,530 cannabis growers from 11 countries (described below) (5).The phase one survey subsequently also ran in New Zealand and Israel (6). Since that time, the GCCRC has grown to 30 collaborators from 24 organisations in 16 countries (see box).

Why did we undertake this research?

Our initial transnational study aimed to better understand who is involved in domestic, primarily ‘small-scale’, cannabis cultivation, the diversity in cultivation practices and motivations, growers’ experiences with and involvement in criminal activity, use of cannabis and other drugs, and their attitudes to different cannabis control policies. We knew the academic research published to date didn’t reflect the reality of these small-scale growers and we appealed to them to ‘set the record straight’ by participating in our research.

What did we do?

Our methodology has been described in detail elsewhere (7-9). The GCCRC developed a 35-item online survey, the ICCQ (10), designed to facilitate international comparisons into the relatively under-researched but increasingly significant phenomenon of domestic cannabis cultivation. In addition to the core set of 35 items, it included optional modules on such topics as: growing practices; growing for medical use; attitudes to policy; and criminal careers and networks. With a survey instrument developed with participatory input from cannabis cultivators from online growers forums, we chose to use Internet-mediated research methods to facilitate dialogue with online groups of anonymous cannabis growers, access large numbers of cannabis growers anonymously from diverse locations, and enable global collaboration with limited project funding (8). Recruitment for the project involved a broad range of varied methods including: Twitter; engagement with and advertising on online cannabis forums; posting on Facebook cannabis culture sites; mainstream media articles (radio, TV, newspaper); distributing flyers and cards at festivals, headshops, alternative music stores, etc.; online and hard copy advertisements in cannabis press and websites; and using social media sharing buttons. Importantly, recruitment strategies differed across countries, reflecting the different cannabis culture contexts and typical activities in those countries (8). The Australian version of the questionnaire was hosted on Qualtrics®, which was linked to the project website,, where potential participants were linked to a flag for one of the host countries (11), plus a ‘rest of the world’ option, then to participant information and consent forms and finally to the questionnaire in their language. Eligible respondents had to be over 18 years of age, to have grown in the past 5 years, and to have completed at least half of our core ICCQ survey.

Although limited by producing self-report data from a non-representative, convenience sample, the online survey method was at least as good as the alternatives, such as representative samples, which seldom reach large numbers of cannabis growers, and justice data, which are skewed towards large criminal networks (7). We adopted questionnaire design, data cleaning and statistical methods to reduce problems of multiple responders in web surveys, and we are confident that these appeared effective (5, 8).

What did we find out in phase 1?

After data cleaning we were left with a sample of 6,530 eligible responses from cannabis growers in 11 countries. Overall, we found a great deal of similarity across countries in terms of: demographic characteristics; experiences with growing cannabis; methods and scale of growing operations; reasons for growing; use of cannabis and other drugs; participation in cannabis and other drug markets; and history of contacts with the criminal justice system. In particular, we found a clear majority of small-scale cannabis cultivators who responded to our survey were primarily motivated for reasons other than making money from cannabis supply and had minimal involvement in drug dealing or other criminal activities. Overall, we concluded that these growers were generally not engaged in criminal activity, beyond their cannabis growing and use. (5)

More specifically, we found that 92% of the sample were male, and the mean age was 27 (IQR 22-36). Some 41% were in full time employment, 65% in some kind of employment and only 7% said they were unemployed. On average, respondents were 20 when they grew their first crop (IQR 18-25), 15% had harvested 1 crop and 42% 2-5 crops. Two thirds (67%) succeeded at their first crop and 83% by their second. Half (49%) grew indoors, 20% outdoors and 31% both. The median number of mature plants they grew per crop was 5 (IQR 3-9) and the space they typically used to grow was 2sqm. Almost all (97%) were growing to use the cannabis themselves, 23% sold some of their harvest to cover growing costs and 13% were growing to sell for profit. Of those selling, 68% said they generated 0-10% of their total income from growing cannabis. Overall, 79% of growers we surveyed said their likelihood of coming into contact with police as a result of their growing was ‘low’ or ‘very low’, and 86% had never had any contact with police because of their growing. (5)

Subsequent analyses of special-topic modules revealed some further insights from the first phase of our study. Compared to recreational growers, medical cannabis growers were more likely to strive to be informed about the content of their cannabis. Medical growers may also be attempting to grow more potent THC but not CBD cannabis (11). In analyses focussing on small-scale growing cannabis for treatment of medical conditions in Australia, Belgium, Denmark, Finland, Germany and the UK (N = 5313), growing cannabis for medical purposes was widespread. The majority of medical growers reported cultivating cannabis for serious conditions. Most of them did have a formal diagnosis. One fifth had received a recommendation from their doctor, but in most cases cannabis use was self-medication that was not discussed with their doctors. (12). Further analyses comparing those who reported growing for recreational, medical and both reasons found that those growing cannabis for medical reasons form a heterogeneous group of people, claims of medical use are not simply an attempt to justify personal cannabis consumption, but do at least partly reflect a genuine belief in medical benefit (13).

One paper involved analysis of 1,722 growers from our sample in Australia, Denmark and the UK, who were asked in more detail about their cannabis growing practices, including the use of harmful chemicals, notably Plant Growth Regulators (PGRs). These chemicals have been banned from food crops for decades, but have been found unlisted in cannabis growing nutrients sold online or in hydroponic stores. This study found that, overall, 44% of growers in these countries reported using any chemical fertilisers, supplements or insecticides, but problems associated with product labelling and uncertainty regarding product constituents made it difficult for growers and the researchers to determine which products likely contained PGRs or other harmful chemicals (14). Furthermore, in terms of growing method, while 40% grew in sunlight and soil (highest in Australia 56%), and 46% grew by hydroponic means (artificial light and roots in a non-soil medium, 29% in Australia), 15% grew under artificial light in soil (14% in Australia) (14), a growing method that has received little attention in previous research.

A qualitative analysis of the, often copious, comments we received in a final open text field, where respondents were given the opportunity to provide further comments, suggested that, overall, the survey was very well received by cannabis growers who completed it. Some 37% of respondents left comments expressing positive appreciation of the study and the research instrument, and expressions of gratitude to the researchers for conducting the work. This contrasts with the 8% of the sample who made negative, critical or sceptical comments about the work. (15)

What are we doing in phase 2 and why?

The first phase of this research helped challenge stereotypes about people who grow cannabis, generated more than 20 academic papers, and informed cannabis policy considerations in several countries, including the decision to decriminalise use and small-scale cultivation in the ACT. So the data has relevance, but needs to be updated. As we are all aware, the global cannabis policy landscape has significantly evolved over the past decade and there are questions about how these new policy settings may be influencing domestic cannabis growers. In particular, since our first survey, a number of new legal and regulatory regimes have been introduced across the world, including the legalisation of cannabis for recreational use in Canada, Uruguay, and in multiple states of the US. As the cannabis policy debates continue around the world, we believe decisions should be informed by current knowledge of the markets involved, including the role played by cannabis cultivation. Additionally, the impact of COVID-19 and associated restrictions on cannabis cultivation is an important topic to investigate.

Against the backdrop of these new developments, the GCCRC has developed a second global survey of cannabis cultivators (the ICCQ 2.0), again targeting small-scale growers. However, the group of researchers has expanded to now cover 18 countries (adding France, Italy, Portugal, Uruguay and Georgia). To aid transnational statistical comparisons, the ICCQ 2.0 is designed as a single survey on the Qualtrics® platform, translated into 12 languages, and individually tailored for each country.

Topics covered in the ICCQ 2.0 include: the characteristics of people who grow cannabis; how they grow and why; personal use of cannabis and other drugs; participation in the illicit drug market and other illegal activity; and impacts of COVID-19. Special optional modules selected by different countries include: conflicts and victimisation; growing for medical reasons; cannabis clubs and activism; opinions on alternative policies for growing cannabis; strains/varieties; and cannabis cultivation in legal markets.

From this new survey we are aiming to again hear directly from cannabis growers about their motivations, practices and experiences of these laws and policies and other factors that affect them. Results will again be used to provide realistic and up-to-date information about cannabis growing to continue to inform consideration of policies, laws and regulations surrounding cannabis cultivation. Furthermore, by looking at such factors through an international comparative lens, we will be able to comment on how different legal and other conditions impact on people who grow cannabis.

Obviously, a cross-national endeavour such as this is a time-consuming and costly project. While most partners continuously try to obtain funding from local sources to set up the survey in their individual countries, much of the work has relied on the enthusiasm and voluntary efforts of the researchers themselves. The group also has a policy not to take funds from companies or others with a direct vested interest in the issue.

The GCCRC is now appealing to growers to have their say so our researchers are ready and able to voice their experiences and opinions when important policy opportunities arise. To complete the survey, growers can head to our website and locate the survey link for their country:


Thanks to our research colleagues from the GCCRC and the cannabis growers who informed, promoted and have completed our two surveys.




1.      Decorte T, Potter GR. The globalisation of cannabis cultivation: A growing challenge. International Journal of Drug Policy. 2015;26(3):221-5.

2.      Decorte T. Domestic cannabis cultivation in Belgium: on (un)intended effects of drug policy on the cannabis market. In: J K, editor. Cannabis in Europe: dynamics in perception, policy and markets. Lengerich: Pabst Science Publishers; 2008. p. 69-86.

3.      Hakkarainen P, Frank VA, Perälä J, Dahl HV. Small-Scale Cannabis Growers in Denmark and Finland. Eur Addict Res. 2011;17(3):119-28.

4.      Decorte T, Potter G, Bouchard M, editors. World Wide Weed: Global Trends in Cannabis Cultivation and its Control. Farnham: Ashgate; 2011.

5.      Potter GR, Barratt MJ, Malm A, Bouchard M, Blok T, Christensen A-S, et al. Global patterns of domestic cannabis cultivation: Sample characteristics and patterns of growing across eleven countries. International Journal of Drug Policy. 2015;26(3):226-37.

6.      Wilkins C, Sznitman S, Decorte T, Hakkarainen P, Lenton S. Characteristics of cannabis cultivation in New Zealand and Israel. Drugs and Alcohol Today. 2018;18(2):90-8.

7.      Barratt MJ, Lenton S. Representativeness of online purposive sampling with Australian cannabis cultivators. International Journal of Drug Policy. 2015;26(3):323-6.

8.      Barratt MJ, Potter GR, Wouters M, Wilkins C, Werse B, Perälä J, et al. Lessons from conducting trans-national Internet-mediated participatory research with hidden populations of cannabis cultivators. International Journal of Drug Policy. 2015;26(3):238-49.

9.      Barratt MJ, Bouchard M, Decorte T, Vibeke Asmussen F, Hakkarainen P, Lenton S, et al. Understanding global patterns of domestic cannabis cultivation. Drugs and Alcohol Today. 2012;12(4):213-21.

10.   Decorte T, Barratt M, Nguyen H, Bouchard M, Malm A, Lenton S. International Cannabis Cultivation Questionnaire (ICCQ) (Version 1.1). Global Cannabis Cultivation Research Consortium. Accessed at (Accessed 14 April, 2014); 2012.

11.   Sznitman S, Barratt MJ, Decorte T, Hakkarainen P, Lenton S, Potter GR, et al. Do medical cannabis growers attempt to produce more potent cannabis products than recreational growers? Drugs and Alcohol Today. 2019;19(4):251-6.

12.   Hakkarainen P, Frank VA, Barratt MJ, Dahl HV, Decorte T, Karjalainen K, et al. Growing medicine: Small-scale cannabis cultivation for medical purposes in six different countries. International Journal of Drug Policy. 2015;26(3):250-6.

13.   Hakkarainen P, Decorte T, Sznitman S, Karjalainen K, Barratt MJ, Frank VA, et al. Examining the blurred boundaries between medical and recreational cannabis – results from an international study of small-scale cannabis cultivators. Drugs: Education, Prevention and Policy. 2017:1-9.

14.   Lenton S, Frank VA, Barratt MJ, Potter GR, Decorte T. Growing practices and the use of potentially harmful chemical additives among a sample of small-scale cannabis growers in three countries. Drug and Alcohol Dependence. 2018;192:250-6.

15.   Decorte T, Malm A, Sznitman SR, Hakkarainen P, Barratt MJ, Potter GR, et al. The challenges and benefits of analyzing feedback comments in surveys: Lessons from a cross-national online survey of small-scale cannabis growers. Methodological Innovations. 2019;12(1):2059799119825606.