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Moldy Weed: Here’s How To Fix It

Moldy Weed: Here's How To Fix It


Moldy Weed: Here’s How To Fix It

Moldy weed can show up at any time, and when it does, it can be devastating. Fortunately, there are things you can do to address this problem. Here’s how to spot mold and stop it before it wrecks your entire harvest.

How To Spot Moldy Weed

Moldy Weed: Here's How To Fix It

Moldy weed can sometimes be hard to identify. That’s because it’s easy to confuse mold and trichomes. Trichomes are the hair-like structures that cover a cannabis plant and that look like little white crystals. They’re what produce and store most of the cannabinoids.

If a bud is covered in a lot of trichomes it can sometimes look like mold. To distinguish between the two, look closely. Mold will typically look like white, gray, black, or brown fuzz, and it will grow both on the surface of the plant and on top of the trichomes.

Moldy weed will also smell weird. Watch out for herb that smells like grass or hay, or that has the general stench of funky rot. You know what good weed smells like, so if it doesn’t smell like good weed it could be moldy weed.

Why Moldy Weed Is Bad

Moldy Weed: Here's How To Fix It

To start things off: never smoke moldy weed. It’s too risky. Anytime mold starts growing, you have to cut your losses and toss the infected bud. If you don’t, there is a high likelihood that the mold will spread to other parts of the plant and you will lose your entire crop.

It’s important to get rid of moldy weed because inhaling mold spores can be very dangerous. That’s especially true if you already have a weakened immune system. Breathing in a lot of mold spores can lead to a number of health problems including:

  • lung irritation
  • asthma
  • a variety of allergic reactions
  • headache
  • cough
  • pneumonia
  • chest pain
  • and more.

The bottom line: getting mold spores in your lungs is dangerous. And if you’ve got even a little bit of mold on your weed, then that means it’s spreading spores all over the place. Your only safe bet at that point is to toss the contaminated plant and try to protect everything that hasn’t been infected yet.

Prevention Is Key

Moldy Weed: Here's How To Fix It

The only real way to fix moldy weed is to prevent it from growing in the first place. Moldy weed occurs most often when the plant is grown or stored in the wrong type of environments. Most commonly, it has to do with temperature and humidity.

There are mold spores pretty much everywhere. In fact, when researchers at NASA grew plants in space some of them got moldy. There really is no way to avoid the presence of mold spores. Instead, the trick is to avoid the environments that allow those spores to set in and grow into full-blown mold.

Certain types of molds thrive in conditions that are humid and warm, where there is little air circulation. Other molds thrive in cooler environments that have high humidity levels. Here’s what you need to do to avoid these conditions.

Humidity and Temperature Control

When you are growing cannabis, you need to keep a close eye on humidity levels and temperature. To do this, you need to have a hygrometer (measures humidity) and a thermometer (for temperature) in your grow room. Check them regularly.

During the early stages of your plant’s life cycle, you need more humidity, sometimes as high as 70 percent. When the plant moves into the vegetative stage, decrease it to between 40 and 70 percent. And when it reaches the flowering stage, humidity needs to be down around 40-50 percent. Some growers drop it down to 30 percent when it gets really close to harvesting time.

As far as temperatures go, never let your grow room get any hotter than 80 degrees Fahrenheit or any cooler than 68 degrees. Shoot for a nice, comfortable 75 degrees throughout the growing process.

Air Circulation

To prevent mold, you need to have good air circulation. Molds are most likely to develop when air is stagnant. To maintain proper air circulation, be sure you have plenty of fans in your growing space. Similarly, you need to have an effective ventilation system to be sure that fresh air is constantly moving into the grow room.

You want enough airflow that the leaves of your plants are constantly moving, but not so much that they’re getting thrashed around.


When your plants are large and they have tons of leaves, they can become especially vulnerable to mold. That’s because all that foliage creates more humidity and makes it harder for air to circulate.

To avoid this, defoliate your plants when they get really big. Carefully remove large leaves, but leave enough in place so your plant can continue growing. Defoliating will make it easier for air to move around your plant, and will make it harder for mold to set in.

Dry and Cure Correctly

When your plants have produced mature buds and it’s time to harvest, be sure you dry and cure them properly. When you dry your buds, hang them upside down in a room that is 70 degrees Fahrenheit and that has 50 percent humidity. As always, be sure there is a constant, gentle flow of air. Leave them there until they start feeling dry.

From there, it’s time to cure them. Place the dried flower in glass jars and store them in a dark location. It should be around 70 degrees Fahrenheit with humidity levels around 60-65 percent. Open the jar once a day to release the old air and let in fresh air. Properly dried and cured buds should feel dry but still slightly sticky. They should have a strong odor, but should never smell like grass, hay, or overly funky.

Store Your Bud Properly

Even after flower has been harvested, dried, and cured correctly, it can still grow mold. Proper storage is the way to avoid this. You should keep your bud in an airtight container away from direct light. As always, avoid exposing it to extreme temperatures—a good room temp of 75 degrees or so is best.

What If Mold Still Shows Up?

Moldy Weed: Here's How To Fix It

If you still end up getting mold on your plants, there is one last-ditch thing you can do. Assuming you catch it early, you can try applying an all-natural, organic fungicide. Look for something that uses only natural ingredients—pure thyme extracts are often used—and avoid chemicals.

Remember that whatever you spray your plants with will ultimately wind up in the finished buds. But if you catch the mold early enough, and you use an all-natural, organic fungicide you may be able to kill the mold without introducing too many harmful contaminants to your plant.

If your plant develops mold, you should also carefully remove the moldy sections of your plant. Very gently snip away the infected portions, and be sure that you don’t let them come into contact with the healthy parts of your plants. You’re trying to minimize the spread of spores, so do your best to keep the infected plant matter away from the uninfected parts.

As far as getting mold on your dried and cured buds, there really isn’t you can do about it. Do not try cutting away the moldy portions and then using the rest. If there’s mold on one part of a nug, it will have already spread spores to every other part of the nug as well. Just toss it. It’s not worth running the risk of consuming contaminated and moldy weed.

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