Medically Reviewed by
Jason Crawford

Article Last Updated on January 4, 2023

Cannabis a-la-mold doesn’t sound too appealing, does it? While this can often be a problem on the black market, even legal dispensaries sometimes have moldy cannabis problems. 

While mold is a big problem for cannabis growers since they have to throw away their product, it’s an even bigger problem for recreational and medical cannabis users as smoking moldy weed can be dangerous for their health. 

Below, we’ll give you tips on how to spot mold growth on your cannabis buds and prevent it from ever entering your pipe, joint, or edible.

The 411 on Mold

Mold is a type of fungus which reproduces via airborne spores. While in small quantities it isn’t dangerous since the immune system prevents any damage, it can be really harmful when ingested in larger quantities.

The most common types of mold include Botrytis cinerea (bud rot), Mucor, Rhizopus, Cladosporium, and Penicillium (Penicillin).

Mold can be found on all kinds of flowers and plants including the cannabis plants. It quickly spreads in humid conditions without proper ventilation. In cannabis, mold can develop in earlier stages of cultivation like overly humid grow rooms, but also if the weed isn’t properly dried and is placed in an airtight container.

What if You Ingest Moldy Weed?

Mold spores can survive high heat, which is why they don’t get destroyed when decarbing. They also thrive in humid conditions with poor air circulation and that should be reason enough for marijuana growers to make sure they have proper ventilation in their grow rooms.

When ingested by people who are allergic to penicillin, it can cause an allergic reaction, and some molds even produce potential carcinogenic mycotoxins.

When inhaled, moldy weed can be the reason why some immunocompromised people develop a lung infection. Moreover, molds like Aspergillus, Mucor, and others may cause fungal infection and other problems in both recreational and medical marijuana users.

Once contaminated, moldy weed needs to be thrown out since it can’t be cleaned or destroyed by high heat.

Types of Mold Found in Cannabis

Powdery Mildew

This type of mold can be mistaken for young trichomes by newbies as it resembles dust that has formed on the leaves and buds, although white mold and trichomes are nothing alike. If left untreated, powdery mildew can quickly spread to other plants and ruin your whole yield. 

White mold thrives in places with a small amount of airflow. If your plants become infected, it’s best to immediately throw away the infected plants in order to prevent them from spreading.

Powdery Mildew vs Trichomes

Trichomes are the shiny, sticky crystals that appear on the buds and leaves of cannabis plants and are responsible for weed’s cannabinoid and terpene content. However, powdery mildew can sometimes be mistaken for trichomes by unseasoned growers or cannabis users. 

Mold, on the other hand, has a grayish-white coating and a powdery appearance which is how experienced growers and users tell it apart from trichomes. Moreover, mold has a specific odor which is often noticed even before you see it. Mold infestation on weed has a musty smell which reminds users of hay – and that’s how you’ll be able to tell that your weed has been infested.

If you think that your weed plants have been exposed to mold, remove the parts that have been infested in order to prevent them from contaminating other plants.

Grey Mold (Botrytis Cinerea)

Grey Mold, botrytis cinerea, or bud rot, is a type of mold that develops from the inside out and it happens if too much moisture is trapped inside the colas. Common signs of mold development include a limp cola, dying leaves, and parts of the plant looking like they aren’t thriving. 

Check for grey mold by inspecting the affected colas. If they have mold, remove the affected parts from the plant in order to save the rest of it. 

Indoor cultivation can also result in the appearance of grey mold when the cultivating conditions are overly moist and humid, while mold in outdoor cultivation can happen as a result of heavy rainfall.

Checking for Moldy Weed

There are several ways to check if your cannabis plants are mold-free and we’ll include some of them below.

Take a Close Look at Your Stash

The best way to check for mold in your stash is to take a closer look at it. In general, mold can be spotted by the naked eye if you know what you’re looking for. 

Powdery mildew presents itself as kief, while spider mites can produce webbing on the flower which also shouldn’t be smoked. Signs of mold include dark spots on green buds, various colors of fuzz, or slimy parts of the plant.

Take a Whiff

Terpenes found in weed produce a wide variety of different aromas ranging from exotic fruits to pine aromas. But, moldy weed has a different smell which can be musty, wet, and can leave a sour taste in your mouth.

That being said, sniffing your stash isn’t a foolproof method of detecting mold. Some molds might not produce a smell, while in others you can’t detect the mold if the infestation only just happened.

Use a Microscope or a Magnifying Glass

If the infestation has just started, you may not be able to see it with the naked eye. In order to inspect the bud more thoroughly, you can use a magnifying glass or even a microscope to check for mold spores in your bud. 

It’s a good option to browse the internet to see how certain molds and fungi look so you can have a reference to compare what you’re seeing under the microscope. 

You could also try to put your bud under a black light, as molds in general look unnaturally green when they’re illuminated by black light.

Check Online

It’s always a good option to be informed and check local media to see if any reports have been made for someone selling a moldy batch of weed. It’s always best to buy weed from licensed dispensaries that sell lab-tested weed because apart from mold, untested marijuana may not only contain pesticides, fungicides, and microbial substances, but can also be laced with other drugs and adulterants which can be even more harmful to your health. 

How to Prevent Your Cannabis From Getting Moldy?

To prevent mold in cannabis, you need to grow the plants in optimum humidity with an appropriate temperature, proper lighting, and a regular inspection during the growing process. Tailor the grow room to the specific cannabis strain you’re cultivating. Optimum humidity levels can range from 59% to 63% (more or less depending on the strain).  

Mold can even appear in improperly cured and dried weed, and to avoid that, allow the flower to dry completely before you place it in any kind of airtight container. The drying process can last about seven days and it should be done correctly so you can preserve the terpenes and trichomes.

After that, all you need to do is store it in a cool, dry place. Don’t opt for a fridge or a freezer as extensive moisture can produce mold. Keep the buds at a storage temperature of below 77 degrees Fahrenheit.

In the end, if you decide to cultivate cannabis, you need to do it right. Since moldy marijuana ingestion can result in a lot of side effects and harm the consumers’ health, marijuana growers need to be extra careful in order to avoid that.

A passionate advocate for the benefits of cannabis. Fraser Horton, who has a background in botany and a strong love of nature, has spent years researching how cannabis affects the body and mind. He established Leaf Nation in 2020, where he has devoted himself to educating people about the legalisation of marijuana and its safe and responsible use. Fraser is committed to highlighting cannabis’ potential for improving wellness and working to dispel the stigma associated with its use.


The information presented on this page is provided as a public service to aid in education and is derived from sources believed to be reliable. Readers are responsible for making their own assessment of the topics discussed here. In no event shall Leaf Nation be held reliable for any injury, loss or damage that could happen if using or abusing drugs.