Plant Growth Regulators, often abbreviated as PGRs, are a class of chemical substances used in agriculture to manipulate the development of plants. Their application in cannabis cultivation has become a point of discussion for consumers concerned about the quality and safety of the product they purchase. These compounds are employed by some growers to alter the physical characteristics of the plant, primarily focusing on the flower’s appearance and overall yield. Understanding the nature of PGRs is important for buyers seeking to make informed decisions about the cannabis they consume.
Defining Plant Growth Regulators
PGRs are chemical messengers that significantly influence a plant’s physiological processes, even in minute concentrations. Plants naturally produce internal hormones that regulate functions like growth, cell division, and flowering. These natural compounds include auxins, gibberellins, cytokinins, abscisic acid, and ethylene.
The term “Plant Growth Regulator” encompasses both these natural hormones and synthetic compounds engineered to mimic or inhibit their effects. Synthetic PGRs are designed to elicit a specific, exaggerated response for commercial purposes. While natural PGRs, such as seaweed extracts, are generally considered safe, the synthetic versions cause the most consumer concern.
Purpose and Application in Cannabis Cultivation
The primary motivation for using synthetic PGRs in cannabis is to maximize profitability through increased yield and altered appearance. Cultivators apply these chemicals to force the plant to divert energy toward flower production and away from vegetative growth. This manipulation often results in a faster transition to the flowering stage, shortening the overall cultivation cycle.
Many synthetic PGRs work by inhibiting the biosynthesis of gibberellins, a natural hormone that promotes stem elongation. This inhibition causes the plant to develop shorter internodal spacing, forcing flower sites closer together and creating denser buds. This increased density results in a physically heavier product, making the crop more lucrative.
Health and Safety Concerns for Consumers
The central safety concern involves consuming cannabis that retains residues of specific synthetic PGRs, especially when combusted. Compounds like Paclobutrazol, Daminozide, and Chlormequat chloride are either banned for use on consumable crops or carry known health risks. Since these chemicals are not intended for human inhalation, they pose health threats when smoked or vaporized.
Paclobutrazol breaks down into nitrosamines when exposed to high heat; these are carcinogenic compounds also found in tobacco smoke. Exposure to Paclobutrazol has also been linked to liver damage and toxicity in mammals. Daminozide, classified by the Environmental Protection Agency (EPA) as a probable human carcinogen, was banned for use on food crops in the United States in 1989.
Chlormequat chloride promotes bushier growth and denser flowers. Although not classified as a carcinogen, it has been associated with skin and eye irritation and potential organ damage at higher exposure levels. Furthermore, these chemicals can reduce the natural levels of beneficial cannabinoids and terpenes, diminishing the quality and therapeutic profile of the final product.
Identifying PGR-Treated Plants
Consumers can look for several characteristics indicating potential PGR use, starting with the physical appearance of the flower. PGR-treated buds are often unnaturally dense, feeling extremely hard when squeezed, and lack the typical irregular structure of naturally grown cannabis. Other visual cues include a lack of visible trichomes, a muted aroma and flavor due to reduced resin production, and excessive brown or unnaturally bright orange pistils. Although these visual cues provide strong suspicion, third-party laboratory testing is the only definitive method to confirm the presence and concentration of synthetic PGR residues.