Cannabis Science

Moldy Weed Signs and Risks

marijuana plant

Mold is notorious for ruining things. From our food to our house, mold can really interfere with our lives. Unfortunately, weed is not exempt from being affected by mold. Mold can take over marijuana when it’s growing or appear over time on the bit you stored away for your blunt. Here’s what you need to know about moldy weed and how to prevent it. 

Photo: Unsplash

What Does Moldy Weed Look Like?

Before you start to prep your weed for consumption, check it for mold. Mold often looks like a greyish white on the bud. Healthline cautions stoners not to mistake mold for the trichomes. Trichomes, the structures that give weed its smell, do not look powdery. Mold is powdery looking while trichomes seem to glitter. 

The photo below is an example of weed with mold on it. 

moldy weed
Source: The Berkshire Edge

If you don’t trust your eyes, you can trust your nose. Mold has a smell, Healthline describes the smell as musty, mildew, or like hay. 

What Does Mold Look Like on a Growing Marijuana Plant?

If you’re a grower, you may want to know how to spot mold on your marijuana plants. Mold can show up in different ways.

According to Royal Seed Queens, botrytis, also called grey mold can show up as small black dots. However, you may also see grey patches of fungi on the plant. 

You may also notice a powdery white substance on your leaves. Royal Seed Queens refers to that as powdery mildew and yup, it’s a fungus. 

Another common fungus to attack cannabis plants is sooty mold. It’s characterized by areas of patches that resemble soot. 

How to Fix Moldy Weed

If you’re wondering how to fix the moldy weed you’re about to smoke, we have some bad news. Mold means your weed has gone bad and should toss it. It’s not as simple as just removing the fungus, the weed could still make you sick.  

However, if you’re wondering how to remove fungus from your growing plant, you’re in luck. Here is how to treat fungus according to Royal Seed Queens:

  • Botrytis – Prune the infected portions. Remove those infected portions from your garden or burn them. 
  • Powdery Mildew – Wipe it off with a damp towel and spray the plant with neem oil foliar spray.
  • Sooty Mold – Get rid of the insects. This type of mold is associated with a bug infestation of the plant. Afterward, use biodegradable plant-safe soap to remove the mold. Spray the plant with it first. Next, wash off the plant and then dry it. Don’t forget to be gentle. 

Can Smoking Moldy Weed Kill You?

Chances are, smoking moldy weed won’t kill you. However, if you’re immunocompromised or have a lung condition moldy weed can seriously harm you and even kill you. 

According to Healthline, fungal species such as Aspergillus, Mucor, and Cryptococcus can cause deadly infections in the lungs of people who are immunocompromised. As a matter of fact, these fungi can affect the central nervous system (CNS) and brain in people with a compromised immune system. 

If your immune system isn’t compromised, you’re not totally safe. Healthline says you could experience vomiting, nausea, or coughing.

In addition to that, you could have an allergic reaction to mold. People who are allergic to mold that smoke moldy weed could experience wheezing and sinus pain. 

How to Prevent Weed From Going Moldy

You can actually lessen the chance of mold growing on your weed based on how you store it. Healthline suggests:

  • Store weed a little below 77°F (25°C)
  • Keep weed in a clean, glass, airtight container
  • Store weed in a cool, dark and dry place
  • Add a humidity pack to your container to regulate the humidity

If you’re planting weed and want to keep your plants from getting mold, Royal Queen Seeds suggests:

  • Planting weed in sunlight if you can
  • Regulate humidity in greenhouses
  • Only use clean tools on your plant
  • Make sure there is good soil drainage
  • Provide adequate space between plants 
  • Keep the plants at around 24°C
  • Defoliate plants during the late vegetative phase
  • Use Trichoderma in containers and beds 
  • Opt to grow plants that are naturally resistant to mold


If you’re about to consume your weed and you notice fungus, toss it. Moldy weed can be dangerous, especially for people who are immunocompromised. If you’re not immunocompromised, you could still end up sick. It’s best to just prevent your weed from growing mold by storing it properly.

If you grow your own weed, you may still be plagued by mold. The good news is that you can treat your moldy plants and prevent mold from forming on them in the future. 

Moldy weed isn’t good weed so follow the tips we outlined to prevent your weed from going moldy in the first place. 


About Trevann

Trevann is Stoner Rotation’s Jamaica-based lead writer for the Science section of our cannabis blog. She graduated with honors receiving her Bachelor of Science degree in Molecular Biology from the University of West Indies, Mona. For the last three years, she has covered some of the biggest questions around cannabis and health underpinned with research from supporting studies, medical journals and scholarly articles. Got something on your mind? You can reach her at [email protected].