Moldy Weed

Moldy Weed: Identifying Methods, Health Risks, Causes & Alternatives 2024

Published on: December 30, 2023 April 7, 2024


Moldy weed is cannabis contaminated with mold. Mold spores grow on incorrectly dried, cured, or stored cannabis due to excess moisture.

Mold spores are poised to assault susceptible organic materials. Moldy weed can cause lung infections, allergic reactions, and poisoning.

So, medical and recreational cannabis users must know how to identify, avoid, and dispose of any bud with fungal growth before smoking or vaping. Learn these protective strategies to reduce severe sickness.

What is a Moldy Weed?

Moldy weed is cannabis that has grown mold. Overwatering allows mold spores in the air, soil, or growth environment to proliferate over sensitive cannabis plants.

Tiny mold colonies then take hold if the plant material is not quickly dried under strict climate controls post-harvest.

The fungus releases root-like tendrils that work through buds while releasing toxic compounds.

Consuming weed visibly infected with fuzzy white, grey, or green mold growth poses serious health hazards, including lung infections and poisoning.

All moldy cannabis should be safely discarded as it cannot be salvaged.

How Common is Moldy Weed?

Mold growth is relatively common in cannabis:

  • A 2021 industry survey found over 25% of cannabis flower samples tested positive for mold.
  • Home growers struggle with mold due to difficulties regulating humidity and airflow.
  • Commercial growers also deal with mold despite climate-controlled facilities.

Contamination can occur:

  • During growth and harvesting
  • Improper drying and curing
  • Storage in damp basements or garages
  • Rehydrating dried-out cannabis

The legality of home cultivation in many states has increased cases of moldy weed. Inexperienced growers may unknowingly harvest buds with mold.

Poor drying and curing methods used by illegal growers also cause excess moisture and mold. And black market weed often isn’t tested for mold before the street sale.

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Identifying Moldy Weed

Detecting mold on weed can be challenging. Visible mold is just the tip of the iceberg – mycelium can spread invisibly inside buds.

Visual Signs of Mold

  • White fuzz – powdery mildew appears as white fuzz on leaves and flowers. It later turns grey/brown.
  • Grey fuzz – mature mold growth looks “fuzzy” and forms greyish/brown spots.
  • Black spots – some molds create black or very dark brown spots on leaves.
  • Web-like growth – certain molds have a webbed, hair-like appearance.
  • Discolored leaves – infected leaves turn yellow, die off or drop easily.

Different molds have distinct visible characteristics:

  • Grey mold looks fuzzy and greyish at first before turning brown
  • Black mold spots are dark brown or black.
  • Leaves are covered with white powdery mildew.

But not all infected weed shows obvious visual mold. Invisible mold strands can permeate inside buds even without signs on the surface.

Smell and taste of moldy weed

Moldy buds give off a characteristic musty, damp smell reminiscent of an old basement, compost pile or decaying leaves. The pungent “dank” smell of quality weed is overridden.

Moldy weed smoke is sour and nasty. Coughing, throat discomfort, and lung inflammation might result.

The smell alone is often the best indicator since some molds grow hidden within buds. Take one whiff of a musty odor and contamination is almost guaranteed.

Other indicators of mold growth

Additional signs that generally accompany visible mold growth include:

  • Soft, mushy flowers
  • Wilting, dying leaves
  • White powder residue on hands and grinding equipment
  • Visible webbing when breaking up bud
  • Rock-hard dense nuggets

Monitor your plants closely during the growth phase. Sudden wilting, yellowing, or dying off of leaves indicates an underlying mold problem. Plants struggling to stay alive likely have mold colonising the root systems.

Bud that feels spongy or mushy when handled or seems abnormally dense for the strain can also signal mold taking hold internally.

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Health Risks of Smoking Moldy Weed

Mold contamination makes weed unsafe to smoke. Both mold spores and mycotoxins released by molds can cause health issues:

Short-term health effects

  • Coughing, lung irritation, inflammation
  • Increased susceptibility to other infections
  • Allergies—runny nose, red eyes, rash
  • FluHeadache, nausea, tiredness

When mold spores are inhaled, immunological responses produce coughing, breathing problems, and inflammation.

Mold allergy causes runny noses, congestion, itchy eyes, and body rashes. Mold toxins reduce immunity, causing tiredness, pains, nausea, and flu-like symptoms.

Long-term health risks

  • Chronic lung problems – infections, asthma, bronchitis
  • A weak immune system
  • Liver and kidney problems
  • Cancer risk – from toxic mold byproducts (mycotoxins)

Long-term mold toxicity can create lasting health issues. Chronic respiratory conditions like aspergillosis often arise after repeated exposure.

Toxic mold byproducts damage organs like the liver and kidneys over months and years of bioaccumulation. Studies link mycotoxins with increased cancer risks as well.

Those with compromised immunity from illnesses like HIV or a transplant anti-rejection regimen face amplified threats.

Dangers for specific groups

Mold exposure is especially hazardous for those with:

  • Immunity issues—HIV/AIDS, chemotherapy
  • Asthma, COPD, CF
  • Damaged lungs – smokers, former smokers
  • Allergies and sinus problems
  • Pregnancy – risk to a fetus

Children and the elderly also face amplified threats from mold toxins. Their developing or waning immune systems struggle to detoxify mycotoxins.

Pregnant women risk severe complications and birth defects from toxic mold exposure at crucial developmental stages.

Anyone with existing lung, respiratory, or allergic conditions faces massively heightened sensitivity. Damaged lungs have less ability to trap and expel fungal spores.

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Causes of Moldy Weed

What conditions cause cannabis to become moldy?

Improper storage

Storing weed incorrectly allows excess moisture and mold growth. Common mistakes include:

  • Packing buds in airtight containers too quickly
  • Using non-breathable packaging materials
  • Exposing containers to temperature swings
  • Stacking containers tightly together

Buds stored while still too moist allow mold to thrive unseen. Non-porous plastic bags and glass jars often trap moisture inside.

Temperate fluctuations also create condensation that fuels mold – like moving containers between hot garages and cold cellars.

Improper drying and curing

Rushing the post-harvest drying and curing processes traps moisture inside buds, setting the stage for mold.

Slow-drying over 2-3 weeks in climate-controlled rooms with monitored humidity is vital. Buds left drying only 5-7 days retain too much internal moisture.

Growing conditions

Issues that promote mold growth during cultivation include:

  • High ambient humidity and temperatures
  • Poor air circulation
  • Overwatering plants
  • Overly dense bud structure

Mold outbreaks often happen when grow rooms reach about 50% relative humidity and 75°F. Stagnant, humid air allows spores to thrive.

Excessive feeding in late flowering also makes densely packed buds prone to mold. Preventative thinning opens up bud structure.

Contamination during processing

Processing machine parts contaminated with mold spores can infect batches of weed during the:

Airborne mold gets drawn into ventilation systems or carried on clothing. Improper sanitation protocols spread spores via hand contact or shared tools.

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Preventing Moldy Weed

Proper techniques when growing, processing, and storing cannabis help avoid mold contamination.

Proper storage techniques

  • Use glass over plastic containers
  • Ensure moisture content under 62%
  • Store buds in a cool, dark place
  • Allow airflow between containers
  • Frequently check stored cannabis

The ideal storage spot is around 60°F with consistent 50-55% relative humidity. Light and heat accelerate mold growth. Leaving space between containers prevents humidity buildup.

Despite best efforts, regularly inspect stored cannabis as spores can sneak into even the best jars. Catching mold early minimises losses.

Drying and curing methods

  • Dry buds slowly over 14-21 days
  • Keep room temp/humidity in the ideal range
  • Trim leaves to prevent trapping moisture
  • Burp containers to control interior moisture

Invest in commercial dehumidifiers and humidifiers to maintain proper moisture levels. Slow-dry buds over 2-3 weeks while keeping relative humidity around 45-55%.

Trimming off large fan leaves allows for increased air circulation. Open containers daily to replace humid air inside with drier ambient air.

Maintaining ideal growing conditions

  • Monitor and control temperature/humidity
  • Maximise air circulation with fans
  • Water appropriately and allow soil to dry out between waterings
  • Spread out plants/colas so air circulates
  • Sanitise equipment and remove dust/debris

Dial in temperature and humidity during the growth phase to avoid spikes conducive to mold. Add more fans for continual airflow over plants.

Water only when soils are nearly dry to prevent high ambient moisture. Lollipop and defoliate plants while allowing adequate spacing between sites.

Keep grow areas meticulously clean. Replace central air filters routinely to filter mold spores. Wash hands before entering rooms.

Avoiding contamination risks

  • Disinfect surfaces and tools regularly
  • Wash hands thoroughly before handling plants
  • Keep growing areas and storage rooms clean
  • Inspect plants routinely for any signs of mold
  • Test marijuana batches for mold before distribution

Require employees to wash hands and wear protective clothing when working with plants. Restrict entry to grow rooms and equip them with positive air pressure.

Establish regular disinfection protocols for all equipment, surfaces and tools. Send random samples out for mold testing to confirm the absence.

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What to Do If You Find Moldy Weed?

Discovering mold on your cannabis isn’t the end of the world. Follow these guidelines to decontaminate and prevent future outbreaks.

Disposal methods

If mold is spotted, isolate and properly dispose of contaminated plants:

  • Wear gloves and a respirator mask if handling moldy plants
  • Remove infected plants from the growing area
  • Seal in plastic bags for disposal to avoid spore spread
  • Sanitise hands, clothes, and tools after disposal

Dead plants must be removed swiftly to avoid endangering healthy ones nearby. Bag plant waste securely before transporting it outside through grow facility airlocks.

All workers should wear PPE during disposal to prevent inhaling airborne spores. Sterilise operation areas, clothing and skin after contact.

Decontaminating storage containers

  • Discard porous containers that contain moldy weed
  • Glass and certain plastics can be washed
  • Use hydrogen peroxide, bleach or isopropyl alcohol solutions
  • Rinse thoroughly afterwards with clean water

Hydrogen peroxide solutions effectively kill mold spores lingering inside non-porous containers. Use a 10% dilution ratio for soaking containers overnight before scrubbing clean.

Isopropyl alcohol sprays also work to sanitise storage jars. Rinse thoroughly with purified or distilled water after cleaning.

Preventing future mold growth

  • Identify and correct the moisture source
  • Reduce ambient humidity levels
  • Use dehumidifiers/improved air circulation
  • Ensure drying and curing is slow/gradual
  • Upgrade storage with better containers

Pinpoint areas of excess moisture, allowing mold colonies. Add commercial dehumidification equipment to maintain strict humidity control. Improve natural or mechanical air circulation.

Review and improve drying rooms to slowly dry products. Consider upgraded storage containers like sealed glass or stainless steel.

Alternatives to Smoking Moldy Weed

If you discover your stash has become moldy, do NOT smoke it. Safe alternatives include:

Safe disposal options

  • Composting is not recommended as it risks spreading spores
  • Contact local waste authorities for medical waste guidelines
  • Seal bags securely and include a toxic substance warning

Check if your city or state has medical cannabis waste disposal programs. Otherwise, double-bag moldy weed with toxic substance warning labels before putting it into general trash collection.

Never compost marijuana infected with toxic molds, as mycotoxins persist through the composting process. Spores spread through organic waste facilities and can infect food crops.

Finding reputable sources for cannabis

  • Purchase lab-tested products from licensed dispensaries only
  • Check for state testing criteria and mold compliance regulations
  • Opt for organically grown cannabis where possible

Buying weed legally from reputable dispensaries ensures it’s been tested for potency, pesticides and mold before the sale. Review lab reports for Aspergillus Penicillium levels under 20 CFU.

When possible choose organically grown marijuana as the plants have higher cannabinoid levels and avoid chemical contaminants. Regenerative, sustainable farming methods produce premium smoke.

Seek out dispensaries emphasising product safety and transparency. Avoid black market sources with no verification standards whatsoever.

The risks of smoking toxic mold far outweigh getting high. In legal states, avoiding unregulated black market weed reduces contamination risks. Insist on seeing third-party lab test results.

Frequently Asked Questions

Q: Can you smoke weed with a small amount of mold?

A: No, you should never smoke weed with any visible mold. Even tiny spots likely mean contamination has spread through other parts of the bud unseen.

Molds also produce harmful toxins, so microscopic exposure poses health issues. Play it safe and discard it at the first signs.

Q: Does cooking moldy weed make it safe?

A: Cooking methods like baking with weed don’t effectively neutralise dangerous mycotoxins produced by mold. Studies found toxins persist despite high temperatures.

The risk isn’t worthwhile, given the availability of uncontaminated cannabis to cook with.

Q: Can you vape or make concentrates from moldy buds?

A: Absolutely not. Mold toxins easily carry over into vape oils and concentrates during processing.

Exposure levels actually become more concentrated, so vaping or dabbing moldy weed is extremely hazardous. Vape temperatures don’t eliminate the threat.

Q: How long does weed last before getting moldy?

A: Properly cured and stored cannabis can last over a year before mold risk sets in. Cool, dark places that maintain consistent 60-65 °F temp and around 55% relative humidity prevent mold growth.

After 2 years, the degradation of terpenes and THC makes weed less desirable even without mold.

Q: Can moldy weed be used to make non-inhalable products?

A: Moldy weed isn’t considered safe for any consumption methods. Mycotoxins can’t be neutralised and persist in topicals like balms or ointments as well.

For Severely compromised immune system patients, even skin contact poses some risk. Err strongly on the side of caution and discard fully.

Q: If only the leaves have mold, can I smoke the buds?

A: Visible mold growth means microscopic contamination has likely spread into the buds as well.

Since smoking introduces spores directly into the lungs, the risks outweigh any perceived benefit to separating leaves.

Inspect buds extremely closely and perform a smell test in addition before considering sparing any portion.


Mold is a stubborn adversary for all cannabis cultivators and manufacturers alike.

The insidious combination of excess moisture and suboptimal drying creates the danger zone where spores silently take hold.

Despite our best prevention efforts, the stealthy menace requires constant vigilance during growth, processing and storage to catch early warning signs of contamination.

Unfortunately, once established, disposal is the only safe resource for compromised plants and products.

Though disheartening, consider it a teaching moment to bolster protective protocols that fortify future harvests.

When purchasing cannabis, ensure current microbial testing data is supplied, and failsafes are in place at reputable establishments.

Staying informed on best practices, testing advancements, and legislation around allowable mold counts empowers us to make wise choices.

While the mold threat lingers eternally, education and accountability on all sides provide some comfort.

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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