You’ve probably encountered mold at some point in your life. Old strawberries in your refrigerator, the bread heels in your pantry, your college bathroom that you routinely cleaned only after letters from the health department. There’s no doubt about it – mold is all around us. Under good circumstances, mold is little more than an inconvenience or a waste of food. But when it comes to smoking, moldy weed can be dangerous.

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What Mold Looks Like

upclose image of moldy marijuana, mold on marijuana

You can’t always tell you have moldy weed without the help of a black light or a lens, but here are some tips to help you tell if your weed is moldy:

  • Dark spots or spores
  • White, grey, yellow, or brown fuzz
  • White, grey, or black web-like material.
  • Musty, urine or sweat-like smell
  • Discolored roots

Why Mold is Bad

Mold isn’t exactly a houseguest you invite over with promises of home-cooked meals and superfast Wi-Fi. While some molds are harmless, other types are dangerous. If left alone in a residence, it’s possible for the more troublesome types to cause a respiratory response in those who live there. Symptoms include sneezing, coughing, and sore throat that persists even after a tumbler of Nyquil.

Moldy weed is also dangerous for pot smokers.

Sometimes, people mistake rotten weed for weed that’s laced with other drugs, such as opium

They may experience headaches, vomiting, trouble breathing, diarrhea, and heart palpitations. Pneumonia is also a possibility.

The Causes of Mold

The number one thing conducive to moldy weed is moisture: this is why you’re more likely to find it in your shower than in your wine cellar. A lack of air circulation also helps it thrive, as spores multiply under tight conditions. In grow rooms, fans mitigate this type of welcoming environment, leaving mold less likely to move in and get comfortable. But that doesn’t make your plants immune entirely.

Temperature is important too, as mold can’t flourish in cold conditions (under 40 degrees) or those that are extremely hot (over 100 degrees)

Pot shops in dry climates are typically less affected than those located in areas wet and humid: you might be Sleepless in Seattle because you’ve been up all night drying off your herb. Moldy lemon, mold on a lemon Like us, mold needs food and oxygen in order to survive. It decomposes things such as gypsum board and oak and feeds on those nutrients. While it can’t grow on inorganic material - concrete, for example - it feeds on the dirt and dust concrete harbors. And, of course, it feeds on your marijuana plants. Belly up to the bar, weed is among its favorite meals.

How to Keep Mold Away from Your Plants

The best way to keep mold away from your plants is to understand why it happens in the first place. Is the moisture too high during the drying process? Do you use fruit peels to add flavor to your buds, inadvertently introducing them to fungus? Do you store wet plants in airtight containers? One way to avoid mold is to purchase plants with an increased resistance. Some of the hardiest strains include satori, pineapple express, hashberry, and cannatonic. Still, as many of us know, genetics aren’t the end all be all. Care, environment, and sheer luck - for humans and plants - are other pieces of the puzzle. well-spread-out-marijuana-plants A few recommendations on how to avoid mold include buying strains suitable for your region (for outdoor growth, climate is most important), learning the details of the strain (both minor and major), refraining from planting strains that are risky (mold is very contagious), experimenting with new strains in small quantities, and saving cuttings to use as backups for future mother plants (just in case). You should also grow in an area where your plants will feel a breeze through their leaves, but not so much that they become overwhelmed by wind. Rain is another concern: protect your pot from pours with an overhead tarp (not one placed directly on top of the flowers). If you live an area where dew is common each morning, give your plants a good shake.

When Mold Happens

Cannabis infected mold should be disposed of immediately, not only for human health but also to stop it from spreading to nearby plants. Some people have a harder time than others parting with their buds, mold be damned. But, particularly for those growing commercially, it’s not worth the risk. Plus, smoking moldy weed is sort of akin to Seinfeld’s George Costanza pulling that éclair out of the trash when he thinks no one is looking. Take a lesson from him in regards to fungus-filled hemp: someone’s always bound to notice.