Cannabis Guide: The Dangers of PGR Weed - International Highlife
PGR Weed VS Organic Weed

Cannabis Guide: The Dangers of PGR Weed

By now, most cannabis consumers are aware of the importance of lab testing for molds, pesticides, and heavy metals. These days, many seasoned cannaseurs also insist upon starting with non-GMO seeds, following organic farming practices, curing the flowers slowly, and hand-trimming the buds.

But there’s a serious danger that cannabis consumers seldom hear about—PGR weed.

What Is PGR Weed?

The acronym “PGR” stands for “Plant Growth Regulators.” PGRs are plant hormones that can control various aspects of development, including the shape and size of roots, stems, and leaves. You could think of PGRs as plant steroids.

The petrochemical revolution of the 1930s led to a host of new agricultural products, including chemical fertilizers, pesticides, fungicides, and plant growth regulators. Scientists developed the first PGRs to increase pineapple crops, and agriculturists later applied the chemicals to various other plants.

Cannabis growers employ PGRs for greater yields and heavier buds. These compounds can affect the timing of flowering, shortening the growth cycle for quicker harvests or lengthening the flowering phase for bigger buds. PGRs can also make cannabis plants more resistant to molds and keep them bushy and under the canopy for indoor Sea-of-Green techniques.

Most Common PGRs Used on Cannabis

Despite mounting evidence of the dangers of using PGRs, unscrupulous cannabis growers continue to use these chemicals to boost the weight and yield of their buds so they can make more money. 

Unfortunately, well-meaning growers may also unwittingly use PGRs because they’re included as ingredients in hydroponics products. The three most commonly used PGRs for cannabis are daminozide, paclobutrazol, and chlormequat chloride.


Daminozide, also known as alar, was developed in 1963 mainly for flowers and other ornamental plants. Cannabis growers use this PGR to increase yields. The chemical inhibits leaf and stem growth, leaving more energy for the plant to produce flowers. However, daminozide also decreases trichome production, which lessens terpene and cannabinoid levels. You might see daminozide marketed under the trade names Compress, B-Nine, or Dazide.


Paclobutrazol inhibits normal growth by acting as a gibberellic acid antagonist. Applying this PGR promotes uniform flowering and delays ripening, so the colas will be bigger.

Instead of elongating, the cells continue to divide and pack closely together, creating denser buds. However, that extra weight is mainly water and cellulose. Paclobutrazol also inhibits terpene and cannabinoid production by binding to crucial enzymes.

Chlormequat chloride

Chlormequat chloride also inhibits gibberellic acid. This PGR limits vegetative growth and can make plants bushier with more flowers. Plants treated with chlormequat chloride will also usually be shorter, making them more fit for indoor cultivation. Chlormequat chloride often shows up in agricultural products under the trade names E-Pro, Citadel, and Cycocel.

Other PGRs you may encounter include ancymidol, ethephon, flurprimidol, and uniconazole.

Dangers of PGR Exposure

Not only is PGR weed a real bummer when it comes to flavor and effects, but the buds can also be harmful to your health. The short-term hazards of PGR exposure include respiratory issues, nausea and vomiting, and skin and eye irritation. Long-term exposure may result in lung damage, fertility problems, abnormal fetal development, and lowered antioxidant and amino acid levels in the brain.

Daminozide Dangers

The U.S. Environmental Protection Agency (EPA) has classified daminozide as a carcinogen and banned its use for food products since 1989. The events surrounding the banning of daminozide made national news when actress Meryl Streep testified in front of Congress, and 60 Minutes discussed the compound in a special episode. The “alar scare” resulted in a net loss of over $100 million for the US apple industry alone.

The National Resources Defense Council released a comprehensive report, which includes warnings about daminozide. The report defines daminozide as “a probable human carcinogen that causes multiple tumors at multiple organ sites in animals.” Daminozide seems to be particularly toxic to the lungs, liver, kidneys, reproductive system, and cardiovascular system. 

Daminozide also breaks down into unsymmetrical dimethylhydrazine (UDMH). Scientists use UDMH primarily as rocket fuel. UDMH is another probable human carcinogen that damages organs and causes cells to mutate.

Paclobutrazol Dangers

Smoking weed with paclobutrazol produces nitrosamine, a carcinogen also found in tobacco. Paclobutrazol exposure can damage the liver by swelling hepatic cells and reducing fertility by disrupting the production of sperm.

Chlormequat Chloride Dangers

While chlormequat chloride treatment may make plants and flowers look prettier, it’s not something you’ll want to inhale. Chlormequat chloride has been associated with skin and eye irritation, and the PGR may also cause organ damage. Extreme exposure to chlormequat chloride can cause irregular heartbeats, tremors, seizures, coma, or death.

Environmental Consequences of Using PGRs

PGRs are not only hazardous to humans but also pose a threat to the environment. Residual PGRs can remain in the soil for years, affecting microorganism diversity and causing health problems, mutations, and even death in wild animals.

How to Recognize PGR Weed

PGR-treated cannabis plants produce overly dense, rock-hard buds that weigh much heavier than they appear. The nugs have a spongey texture and tend to look like overly processed, machine-trimmed weed, which is another reason for consumers to choose hand-trimmed cannabis.

PGR buds typically have a dark, dull, brown, or even orange color. It’s easy to confuse PGR weed with overly dry, poorly-cured, or already-vaped buds. Other obvious signs of PGR weed are excessive red or brown hairs and a noticeable lack of trichomes.

Since PGRs inhibit terpene production, the buds will have no taste, aroma, or distinct chemical flavor and smell. Most PGR weed has low cannabinoid contents, although the effects may kick in faster and last longer. However, most consumers experience uncomfortable symptoms like headaches, sweating, or excessive fatigue after imbibing PGR weed.

Common Plant Nutrients that Contain PGRs

Unfortunately, it’s not always easy for growers to know which products contain PGRs. Some nutrient manufacturers disclose PGRs in the fine print of their ingredients lists, while others deceptively omit them altogether. Here’s a partial list of products that either contain or are suspected of having PGRs:

  • Boonta Bud
  • Bushload
  • Dr. Nodes
  • Flower Dragon
  • Gravity
  • Phosphoload
  • Rock Juice
  • Rox
  • Mega Bud
  • Super Bud
  • TopLoad
  • Yield Masta/Sudden Impact

Fortunately, California has banned many of these products, but they’re still available and widely used in other states and countries.

Safe Alternatives to PGRs

The best way to grow fantastic cannabis is through knowledge, hard work, and experience. Learning how to make nutrient-rich supersoil is an excellent first step. You can learn more about all-natural indoor cannabis cultivation by reading the book True Living Organics by the Rev.

Organic cannabis growers often include natural plant growth regulators such as bat guano, seaweed, alfalfa, and crustaceans in their starter soil or compost teas. These organic compounds boost levels of auxins, cytokinins, chitosan, and triacontanol, essentially serving the same purposes of PGRs without the health risks or lowering the quality of the buds. 

Auxins will stimulate the elongation of stems and bud growth, but you’ll want to be careful not to add too much as it will inhibit the growth of lower buds. Adding natural cytokinins will encourage more branch formation and enhance the color of the buds.

Cytokinins also provoke cannabis plants to enter the flowering stage earlier, allowing for more indoor harvests per year.

Chitosan comes from the chitin that forms the hard exoskeleton of crustaceans, such as shrimp, lobsters, and crabs. You can add the remains of your seafood meals directly to your compost pile or buy pulverized chitosan to add to your organic fertilizers or foliar sprays. Chitosan improves photosynthesis and the absorption of nutrients from the soil.

The compound offers the added benefits of strengthening the plant’s disease resistance and boosting terpene production.

Alfalfa meal is a common supersoil ingredient because it contains high quantities of triacontanol. Triacontanol stimulates growth by stimulating essential enzyme activity, increasing the amount of chlorophyll, and enhancing the plant’s ability to absorb carbon dioxide and soil nutrients.

Growers should always keep in mind that more isn’t necessarily better when it comes to these nutrients. As with all things cannabis, start low and go slow. Overdoing it with soil additives, even organic ones, can backfire and produce unwanted effects. When in doubt, let Mother Nature do her thing, and she will reward you with a bountiful harvest.

How to Avoid PGR Weed

Although the “big 3” PGRs have been banned from use on food crops in the US, they remain approved pesticides in most of the EU. Furthermore, since cannabis is yet to be universally legalized, the use of PGRs and other harmful agricultural products is still unregulated. Unfortunately, the lack of regulation means that it’s up to the individual cannabis consumer and grower to ensure that their buds are safe and free of PGRs. 

PGR weed can trick even experienced herb lovers. Cannabis grown with PGRs can look a lot like lower-grade black market or Mexican weed. It may be tempting to take advantage of what seems like an incredible deal for making extractions for edibles or topicals. 

You would think that sticking to lab-tested dispensary cannabis would protect you from PGR weed. But, unfortunately, that’s not the case. Big Ag is heavily involved in the legal hemp and cannabis industry, and many companies put profits over quality.

So, how do you avoid getting fooled by PGR weed? First, look for the tell-tale signs mentioned above:

  • Rock-hard buds
  • Dull-brown or orange coloring
  • Excessive quantities of pistils
  • Lack of aroma or chemical smell

Secondly, buy your weed from trusted sources like local small growers who have a reputation to protect. Lastly, brush up on your gardening skills and grow your own organic buds when all else fails.

This article has been updated on the 31st of October 2021.

6 responses to “Cannabis Guide: The Dangers of PGR Weed”

  1. Good article, very informative

  2. Darcey says:

    I just want some seeds to grow my own because I’m tired of chasing dealers and at 65 I’m old enough to grow my own.
    Where can I get some. I dont want designer just the old fashioned sensameiian or and I can’t remember the name. Itll come to me soon enough

  3. Where can I find organic seeds? I only need enough to grow my own personal plants.
    Also, what is the price?
    What is your opinion on vape pens? Looking for one I trust.

  4. Deb Doyle says:

    I was just talking to a bud tender today and was mentioning that I thought a certain ‘brand’ of flower really caused me to cough and bring up crud. It wasn’t that any of it was sativa, hybrid or Indica. I had the same reaction. He told me about PGR weed and showed me the difference in the way the buds looked. I came home and found your article. Very informative. I am 70 and try to be real careful about what I smoke. Kudos to good bud tenders.

  5. steven burnett says:

    Well for those of us that live in states were we have to rely on our local dealer don’t really have a choice.

  6. Ray W says:

    As a resident of Amsterdam and a frequent visitor to the many great “coffee shops” there, I see many outlets selling dense buds, but as 99% of Amsterdam’s cannabis is grown indoors, I wonder if they are using PGR

    When I ask at the counter, the guys just don’t know, they only sell it, nit cultivate it

    The new trend of “Dutch grown Cali Strains” are often hard buds, but they smell natural, no chemical smells.

    I will be looking into this a little more in the future, that’s for sure

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