About 1 in 4 Cannabis Home Growers Used Chemical Additives, With Rates Declining Over Time | Research

The takeaway

A survey of over 11,000 cannabis growers across 18 countries found 26% used chemical fertilizers or pesticides, with use declining compared to a decade earlier.

Cannabis consumers, home growers, and anyone interested in cannabis product safety and regulation.

26% of growers used chemicals, with soil + artificial light growers making up over half of chemical users

What the researchers found

In the 2020-21 survey, 26% of cannabis growers reported using chemicals. The highest odds of chemical use were among male, older, urban growers who grew under artificial light to sell cannabis. In three countries tracked over time (Australia, Denmark, UK), chemical fertilizer use decreased significantly between 2012-13 and 2020-21.

Why it matters

Unregulated chemical use in cannabis growing poses health risks to consumers, especially since some plant growth regulators banned from food crops for decades have been found in cannabis fertilizer products. Understanding who uses these chemicals and why can inform harm reduction efforts.

The numbers in context

11,479 growers surveyed across 18 countries. 26% reported chemical use. Growers using soil and artificial light comprised over half of all chemical users. Significant reductions in chemical fertilizer use were observed between the 2012-13 and 2020-21 surveys in Australia, Denmark, and the UK.

How the study worked

Web-based convenience survey of 11,479 mainly small-scale cannabis growers from 18 countries (2020-2021). Logistic regression identified predictors of chemical use. Results were compared with data from a similar 2012-13 survey in three countries.

What this study cannot tell us

Convenience (non-random) web sample may not represent all cannabis growers. Self-reported chemical use may be underreported. The two survey waves used different samples, limiting direct comparison.

How to read the evidence

Moderate: large international sample with statistical modeling, though limited by convenience sampling and self-report.

When this study was published

2025 study using 2020-2021 survey data.

The bigger picture

As cannabis legalization spreads, regulating the products used to grow it becomes increasingly important. This study highlights that the legal cannabis fertilizer market itself needs stricter oversight to protect both growers and consumers.

Questions still open

What specific chemicals are most commonly used, and at what concentrations? How do residue levels in harvested cannabis compare between chemical-using and non-chemical growers?

Common questions

What kind of chemicals were growers using?

Chemical fertilizers, pesticides, and plant growth regulators (PGRs), some of which have been banned from food crops for decades but appear in products marketed to cannabis growers.

Which growers were most likely to use chemicals?

Male, older, urban growers who grew under artificial light, used soil or non-soil media, grew to sell, and believed cannabis was legal in their area.

Read the original research

Growing practices and the use of potentially harmful chemical additives from a web survey of mainly small-scale cannabis growers in 18 countries.

The International journal on drug policy, 144(Pt 3), 104662

View on PubMed ↗Publisher’s paper ↗

Citation

Lenton, Simon; Potter, Gary; Fortin, Davide; Granville, Ashely; Grigg, Jodie; Sevigny, Eric; Wilkins, Chris; Decorte, Tom; Barratt, Monica. (2025). Growing practices and the use of potentially harmful chemical additives from a web survey of mainly small-scale cannabis growers in 18 countries.. The International journal on drug policy, 144(Pt 3), 104662. https://doi.org/10.1016/j.drugpo.2024.104662