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The Good, the Bad, and the Ugly: PGRs in Cannabis Cultivation

The Good, the Bad, and the Ugly: PGRs in Cannabis Cultivation

The 420 Gardener

Plant growth regulators (PGRs) have long been a contentious topic in the world of cannabis cultivation. These chemicals can significantly influence plant growth, yield, and quality, but not all PGRs are created equal. While some can be beneficial, others pose serious health risks. Understanding which PGRs to use and which to avoid is crucial for any cultivator aiming to produce safe, high-quality cannabis.

What are PGRs?

Plant growth regulators are chemicals that influence the growth and development of plants. They can be naturally occurring hormones or synthetic compounds. In cannabis cultivation, PGRs are often used to manipulate plant height, branching, flowering, and overall yield.

The Good: Beneficial PGRs

  1. Gibberellins:
    • Function: Promote stem elongation, seed germination, and flowering.
    • Benefits: Using gibberellins can enhance the growth rate of cannabis plants, leading to more vigorous vegetative growth and potentially higher yields. They are especially useful in promoting uniformity in flowering.
    • Usage: Gibberellins can be applied during the vegetative and early flowering stages to stimulate growth.
  2. Cytokinins:
    • Function: Promote cell division and delay leaf senescence (aging).
    • Benefits: Cytokinins help in the development of bushier plants with more branching, leading to more potential bud sites. They also enhance nutrient uptake and overall plant health.
    • Usage: These are often used during the vegetative stage to encourage branching and during cloning to improve root formation.
  3. Auxins:
    • Function: Promote root development and regulate responses to light and gravity.
    • Benefits: Auxins are essential for root development, making them particularly valuable during the cloning process. They help clones establish strong root systems quickly.
    • Usage: Typically used in rooting gels and powders for cloning.

The Bad: Harmful PGRs

  1. Paclobutrazol:
    • Risks: Paclobutrazol is a synthetic PGR that inhibits gibberellin biosynthesis, leading to shorter, bushier plants. However, it is also a known teratogen (causes birth defects) and can be toxic to humans.
    • Health Impacts: Cannabis treated with paclobutrazol can produce smoke that contains harmful compounds, posing risks to consumers.
    • Recommendation: Avoid using paclobutrazol entirely in cannabis cultivation.
  2. Daminozide (Alar):
    • Risks: Daminozide is another synthetic PGR that can cause cancer and other health issues. It is banned for use in food crops in many countries due to its carcinogenic properties.
    • Health Impacts: Cannabis treated with daminozide poses significant health risks to consumers, especially when smoked.
    • Recommendation: Steer clear of daminozide to ensure the safety and health of your consumers.
  3. Chlormequat Chloride:
    • Risks: This PGR is commonly used in ornamental plants to control growth, but it can be harmful if ingested. While not as dangerous as paclobutrazol or daminozide, it is still not recommended for use in consumable crops like cannabis.
    • Health Impacts: Potential for toxicity if consumed in large quantities.
    • Recommendation: Avoid using chlormequat chloride in cannabis cultivation.

My Hawaiian Experience with Natural PGRs

Growing up in Hawaii, I was fortunate to learn from the elders who cultivated cannabis with traditional and natural methods. One of the most memorable techniques was the use of coconut milk during the flowering phase.

Coconut Milk as a Natural PGR:

  • Preparation: The elders would dilute fresh coconut milk with water, creating a solution that was used to feed the plants during flowering.
  • Benefits: Coconut milk is rich in cytokinins and other beneficial compounds that promote cell division and delay aging. This natural PGR not only boosted flower production but also enhanced the overall health and resilience of the plants.
  • Application: Coconut milk can be applied as a foliar spray or added to the soil during watering. It’s an excellent way to introduce natural cytokinins to your cannabis plants without the risks associated with synthetic PGRs.

Natural Alternatives to Synthetic PGRs

  1. Seaweed Extract:
    • Components: Rich in natural cytokinins, auxins, and gibberellins.
    • Benefits: Enhances overall plant health, promotes root growth, and improves stress resistance.
    • Usage: Can be applied as a foliar spray or soil drench during all stages of growth.
  2. Aloe Vera:
    • Components: Contains natural growth hormones like gibberellins and auxins.
    • Benefits: Promotes root development and overall plant vigor.
    • Usage: Aloe vera gel can be mixed with water and used as a foliar spray or rooting solution for clones.
  3. Humic and Fulvic Acids:
    • Components: Derived from organic matter and contain a variety of beneficial compounds.
    • Benefits: Improve nutrient uptake, enhance root growth, and stimulate microbial activity in the soil.
    • Usage: Applied to the soil or as a foliar spray to enhance overall plant health and growth.


Understanding the role of PGRs in cannabis cultivation is crucial for producing high-quality, safe products. While beneficial PGRs like gibberellins, cytokinins, and auxins can enhance growth and yield, harmful synthetic PGRs such as paclobutrazol, daminozide, and chlormequat chloride should be avoided due to their health risks. Embracing natural alternatives, like the coconut milk technique I learned in Hawaii, can provide safe and effective ways to boost plant growth and ensure the health of both the plants and consumers. By focusing on natural and beneficial PGRs, cultivators can maintain the integrity and safety of their cannabis crops while achieving impressive results.

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