PGR Weed Guide Understanding Risks & Solutions

PGR Weed Guide: Understanding Risks & Solutions

Published on: November 30, 2023 December 30, 2023

Introduction: PGR Weed

Plant growth regulators (PGRs) are chemicals used in cannabis cultivation to increase bud size and yields.

However, many popular PGRs like paclobutrazol and daminozide have not been approved as safe for human consumption and get absorbed into the plant’s buds and tissues.

This has raised serious health concerns about the toxicity of residues when smoked or vaped, as PGR weed has been associated with headaches, lung irritation, nausea and a variety of other problematic effects. 

This article explores what these concerning chemicals are, how to identify signs of PGR-treated weed?

The health risks posed by exposure to leftover residues, and how conscientious cannabis cultivators are protecting consumers by avoiding synthetic plant growth enhancers?

What are PGRs in Weed?

Plant growth regulators or PGRs refer to synthetic chemicals used in cannabis cultivation to rapidly increase bud size and yields.

Popular PGR products used include paclobutrazol, daminozide, and chlormequat chloride.

These systemic chemicals get directly absorbed by the plant’s roots and tissues, infiltrating flowering buds.

PGRs stimulate rapid, undifferentiated cell growth that produces woody, inferior buds. They divert energy towards accelerated flowering at the cost of terpene and cannabinoid production.

PGR weed ends up lacking aromatic flavors or therapeutic effects. Visually, plants stretch taller with limited branching as chemicals prompt rapid flowering over healthy development.

While generating big buds quickly, PGRs severely degrade cannabis quality and potency.

Chemicals in floodwater harm plants and buds, causing health issues like headaches, lung irritation, and unknown toxicity from residues. 

Ethical cultivators dedicated to premium medical cannabis thus avoid synthetic plant growth regulators entirely.

They rely on natural cultivation methods for safe, high-quality cannabis that protects consumer well-being.

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Effects of PGRs on Cannabis

The use of PGRs can have several concerning effects on cannabis plants and the buds they produce:

  • Reduction in Desired Compounds: PGRs reduce plants’ synthesis of terpenes, flavonoids, and cannabinoids, which give strains their flavors, smells, and effects. Result: dull, generic buds.
  • Fewer Trichomes: Buds have glossy, mushroom-shaped resin glands called trichomes. PGRs drain plant energy from trichome synthesis, reducing trichomes. These are necessary for high THC levels.
  • Minimal Scent: Due to terpene and trichome reduction, PGR buds have a less fragrance than excellent cannabis. They smell faintly green or hay-like.
  • Poor Combustibility: Experienced users say PGR buds burn badly. They typically fail to ignite and generate heavy black smoke instead of clear white vapor.
  • Harsher Smoke: Even experienced smokers find PGR cannabis difficult to inhale because it produces hot, harsh smoke that may cause coughing fits.
  • Unappealing Appearance: Big PGR buds seem spectacular at first. However, closer observation shows that their bulk and density derive from woody, almost plastic-textured development, not trichome-coated bract clusters.

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Identifying PGR Weed

How can you, as a consumer, spot if a strain has been treated with toxic PGRs? Here are the telltale signs to examine buds for:

  • Unnaturally Dense and Large Buds: This is why growers use PGRs – to swell buds to 2-3 times their normal size. But such hard, heavy buds with crude round shapes are a red flag.
  • Disproportionate Orange Pistils: Pistils or “hairs” grow from buds’ calyxes to catch pollen. PGR weed often has far longer orange pistils relative to actual flowering growth. They also may be oddly darkened or wilted.
  • Lack of Visible Trichomes: Scan buds with a magnifying glass. Quality buds are frosty with thousands of mushroom-shaped, THC-rich trichome glands. PGR buds often have few to no visible trichomes.
  • Hay/Grass Clippings Smell: Take a good whiff of the buds (if possible before purchasing). PGRs ruin the terpene and cannabinoid content that delivers strains’ signature smells.
  • Black Ash: PGR cannabis smokes darker and leaves thick black ash, not powdery like high-quality bud.
  • Harsher Smoke: PGR-grown cannabis on a bong makes even experienced users choke. Smoke has a nasty chemical flavor.
  • Chest Pain: Inhaling remnants from PGR weed’s toxic compounds may cause sore throat, chest tightness, coughing, and headaches.

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Health Risks Associated with PGR Weed

Smoking buds treated with synthetic PGRs poses many potential health hazards:

  • Headaches and Nausea: Both are immediate side effects reported by many PGR weed smokers as the chemicals hit their systems.
  • Respiratory Irritation: The smoke often induces violent coughing fits, sore throats or chest discomfort due to lung inflammation.
  • Impaired Blood Oxygenation: PGR smokers had lower blood oxygen levels than organic marijuana smokers due to lung function issues.
  • Toxic Chemical Exposure: Paclobutrazol and most PGRs used on weed have not been approved as safe for humans to ingest. Their toxicity when combusted and inhaled is still understudied.
  • Liver Function Impairment: PGRs like paclobutrazol can inhibit enzymes, leading to reduced liver function and potential long-term damage.
  • Reproductive Issues: Other concerning research indicates the reproductive toxicity of many synthetic PGRs – both for fertility and fetal/child development.
  • Cancer Risks: Some PGRs (like daminozide) are classified as possible carcinogens. Their health impacts when smoked long-term require more research but likely carry cancer risks.

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PGR-Free Cannabis Cultivation

Conscientious cannabis cultivators avoid synthetic PGRs and instead use natural, ethical cultivation methods for clean, high-quality crops:

  • Organic Feeding: They use only natural organic additives to nurture plants in living soil or hydroponically in recycled plant debris and organic nutrients.
  • IPM Programs: Integrated pest management controls pests responsibly through the introduction of predatory beneficial insects rather than chemical pesticides.
  • Hand Trimming: Favoring hand-trimming over machine-trimming protects delicate trichomes coating buds from getting sheared off.
  • Curing & Storage: Allowing buds to slowly cure via careful temperature/humidity regulation helps fully develop terpenes and flavonoids. Proper storage then prevents degradation.
  • Lab Testing: Third-party lab testing verifies bud potency and purity, ensuring heavy metal, pesticide, and synthetic chemical-free crops.
  • Education: Ethical growers prioritize consumer education around the dangers of PGRs. They teach how to identify signs in weed and see lab testing as essential for health.
  • Advocacy: Responsible producers promote improved cannabis testing and expose corrupt PGR-using grow operations for their health risks.

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PGR-Free Brands and Strains

Seeking out conscientious cannabis producers using natural, ethical methods is key to avoiding PGR weed.

Here are some reputable PGR-free brands and strains to look for:


  • Wonderbrett: This licensed CA brand uses premium organic inputs to craft top-shelf OG strains. All products have lab reports showing 0 PGRs.
  • Legacy Farmers Co: This leading MI brand adheres to the strictest organic protocols. Their lab-tested strains highlight exotic landraces.
  • Nectar Drop: Major WA processor Nectar Drop details extensive quality controls, ensuring all processed bud products are PGR-free.


  • Zkittlez: This sugary, terpene-rich India is prone to smaller, looser buds unenhanced by PGRs when properly grown.
  • Durban Poison: The classic Sativa strain trends lankier with less dense flowering sites – making it less attractive for PGR treatment.
  • OG Kush: Legendary kush strains display classic conic-shaped buds and complex aroma – quickly ruined by synthetic PGR application.

As more states introduce testing regulations, brands publishing independent lab results will become better trusted for PGR-free quality.

PGR Testing Methods

Although home tests are still limited, cannabis labs are honing various scientific methods to accurately detect PGR contamination:

Targeted Tests

  • ELISA Testing: The enzyme-linked immunosorbent assay uses antibodies that bind to specific PGR molecules like paclobutrazol – useful for confirming exposure.
  • LC/MS-MS Testing: Liquid chromatography paired with tandem mass spectrometry allows precise identification of residue from concerning PGR chemicals like paclobutrazol, daminozide and chlormequat chloride. This method can accurately detect PGR levels down to as low as parts per billion concentrations.

Broad-Spectrum Tests

  • Terpene Profiles: Since PGRs severely degrade terpene development, measuring significantly lower terpene concentrations signals abnormal interference from growth enhancers. Complete terpene analysis provides an initial red flag for potential PGR usage.
  • Heavy Metal Screening: Synthetic PGRs’ root absorption mechanisms also uptake toxic heavy metals like cadmium, lead and mercury into plant tissues and buds, showing dangerous contamination.
  • Petroleum Testing: Chemical solvents related to PGR product manufacturing processes can leave petroleum residues like machine oils. General hydrocarbon solvent testing thus also helps identify likely PGR grow ops utilizing commercial products.

Future Testing Approaches

  • Genetic Analysis: Researching changes in gene expression patterns and plant DNA when subjected to synthetic PGR exposure may someday enable rapid genetic screening tests.
  • Morphological Analysis: Machine learning and image processing algorithms to mathematically assess geometric patterns and anomalies in bud structure disrupted by unnatural PGR-driven growth show promise for automated detection.

As testing technology progresses, fast and affordable tests for PGRs as standard practice will enable consumers to avoid hazardous chemical cannabis.

For now, savvy consumers should seek out reliably lab-tested products.

Regulatory Concerns Surrounding PGRs in Cannabis

Cannabis safety advocates argue that inadequate regulations currently leave consumers vulnerable to the use of hazardous PGRs:

  • Unknown Health Hazards: Little to no scientific literature yet explores the health outcomes of inhaling combusted PGR residue. Their interactions with terpenes and plant sugars during heating require urgent study.
  • Non-Validated Testing Methodologies: Since federal prohibition plagued cannabis laboratories, states scurry to set PGR contamination guidelines and detection thresholds when goods hit the market.
  • Inconsistent PGR Standards: Maximum PGR values range from 100 to 5,000 ppb between states. Not all PGRs are regulated.
  • Labeling issues: Although states are unsure about labeling cannabis goods “PGR-free”, pesticides must be labeled. This makes PGR cannabis harder to avoid.
  • Unregulated Sources: Federal prohibition forces cannabis cultivators who cannot sell to licensed markets to utilize unregulated routes, where bulk purchasers typically don’t know about PGR usage. Unregulated items reach many customers.
  • Limited Access to Lab Reports: Reputable companies release product testing data online; however, unlicensed growers seldom give potency/contaminant reports. This lack of transparency hinders merchant and user vetting.

Public awareness and calls for politicians to solve regulatory loopholes may help stop unregulated chemical cannabis production.

Only consumer pressure can force supervision and safeguards against growing weed-boosting poison usage.


People who buy weed and people who make laws need to pay close attention to the growing use of fake plant growth regulators to get bigger buds.

PGR weed bags might look appealing to people who have never seen them before because they are so big and dense.

However, experienced users know that these signs mean the weed isn’t very good because it has weak flavors and a strong aftertaste. 

Even worse, lighting PGR-laced weed puts users at real health risk because they breathe in harmful waste.

Until there are rules in place to keep an eye on PGR pollution levels, people who buy cannabis need to keep an eye out for common signs that buds have been artificially improved. 

It is still important to find brands that you can trust that have clear organic policies and independent lab test results.

Protecting public health in America’s growing legal weed market means educating other users, calling for stricter rules on product testing, and naming people who push PGR.

About the Author

Gaanja Heal

Gaanja Heal’s goal is to give people easy access to medical marijuana resources and qualified doctors. These doctors can evaluate patients to see if medical cannabis may help treat their health conditions.

View all posts by Gaanja Heal

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