Moldy Weed: Identifying and Preventing Mold on Cannabis

Moldy weed is a common issue faced by both growers and consumers. If you’ve stumbled upon this article, you might be wondering if your cannabis is moldy. This article will guide you through identifying moldy weed, the risks associated with consuming powdery mold on cannabis, how to prevent mold growth, and what to do if you find mold on your cannabis.

What is Mold on Weed and Why Should You Care?

Mold is a fungus that can infest cannabis plants during cultivation or even after harvest during storage. It thrives in warm, humid environments with poor airflow. Mold on cannabis not only ruins the quality and potency of your buds but can also pose serious health risks if consumed, especially for people with weakened immune systems. 

Whether growing marijuana at home or purchasing it, knowing how to identify and prevent common types of mold is crucial.

What Does Moldy Weed Look Like?

Mold on cannabis can appear in several forms. Signs of mold appear as white, gray, brown, or black powdery spots or fuzzy patches on cannabis buds. Mold loves to hide in the dense parts of the flower, making it sometimes difficult to spot at a glance. It can also appear as fuzzy white or gray webbing. 

Powdery mildew.

Always inspect your cannabis closely, especially in hidden crevices near the center of the bud.

Moldy Weed vs. Trichomes

Trichomes on a healthy cannabis plant photographed under magnification.

For new cannabis users, distinguishing between mold and trichomes (the tiny, crystal-like structures that contain cannabinoids and terpenes) can be challenging. Trichomes are clear or milky white and give the cannabis its frosty appearance. In contrast, mold is more fuzzy and discolored, often appearing in shades of white, gray, black, or brown. 

Powdery mildew forms next to trichomes, photographed under magnification.

The Risks of Consuming Moldy Cannabis

Consuming moldy cannabis can pose significant health risks. Inhalation of mold spores can lead to respiratory issues, allergic reactions, and infections, particularly in individuals with compromised immune systems and anyone allergic to mold. 

Other conditions like asthma can become more serious around weed mold. Studies have shown that certain molds produce mycotoxins, which are toxic and potentially carcinogenic. Always avoid smoking or ingesting moldy cannabis to prevent these health risks.

How to Tell if Weed is Moldy

Mold is often visible, especially when breaking up or grinding your nugs for consumption. However, if you don’t see any mold on your weed or are unsure if what you’re seeing is mold, rely on your other senses.

Powdery mildew.

Texture and Smell

Moldy weed often feels different from healthy cannabis. It may have a spongy, soft texture, and a musty or mildew smell, like damp, old clothes. Always trust your senses; if something feels or smells off, it probably is. If you come across a moldy weed smell, it’s time to find a dumpster.

Advanced Signs

In severe cases, mold can be more visible, covering large areas of the bud with a white, gray, or black powder or fuzz. This is a sign of serious infestation, and such cannabis should be discarded immediately. If you see powdery mildew on cannabis, it’s time to throw it away.

Preventing Mold on Weed Plants

An ounce of prevention is better than a pound of cure in cannabis cultivation. Here are some tips to keep your cannabis mold-free:

Optimal growing conditions

Mold tends to grow rapidly over temperatures of 80 degrees Fahrenheit. Ensuring a healthy growing environment is essential to prevent mold. Humidity control is crucial for preventing mold indoors. You can achieve optimal relative humidity (rH), which is in the range of 55-60, by using dehumidifiers and oscillating fans. 

Proper air circulation and ventilation are key factors in maintaining a mold-free environment. Ensuring your plants are not overcrowded can further minimize the risk of mold, especially outdoors.

Pruning cannabis is an essential practice that helps prevent mold. Regularly removing dead or damaged leaves helps improve air circulation and light penetration, which are critical in preventing mold, among other pest infestations.

Caterpillar damage is another common issue that can lead to a certain type of mold known as bud rot. These pests typically feed on the leaves and buds, creating entry points for mold and other pathogens. Early detection is crucial; regularly inspecting plants for signs of caterpillars or their droppings can help mitigate damage. 

Biological controls such as Bacillus thuringiensis (Bt), a natural bacterial insecticide, can be effective in managing caterpillar populations. Attracting parasitic wasps can provide natural pest control. Implementing these strategies can help protect your cannabis plants from caterpillar damage resulting in bud rot.

Certain strains, like Sour Diesel, are mold-resistant; they typically contain high levels of Limonene, a terpene known for its antifungal properties.

Storage solutions

Cannabis can become infested with mold after being harvested. Proper storage is crucial to prevent mold after harvest. Make sure your cannabis has been properly cured before trying to store it for a long time. Store your cannabis in airtight containers in a cool, dry place. 

Turkey bags or paper bags can be used for short-term storage, especially during the curing process. Glass mason jars are a popular option for long-term storage. Other cannabis industry-specific solutions like Grove Bags are designed to provide the ideal environment for long-term cannabis storage.

Can Weed Grow Mold After Harvest?

Yes, cannabis can still develop mold after it’s been harvested, especially if it’s stored improperly. Moisture, warmth, and poor ventilation can all contribute to post-harvest mold growth during the cannabis production process. Ensuring your cannabis is thoroughly dried and cured before storage is essential to prevent mold development. You can learn the essentials of harvesting, drying, and curing in this holistic horticulture class series.

Treatment Solutions for Moldy Weed

Powdery mildew looks like powdery white spots on leaves and buds. You can spray your plant with Bacillus and Trichoderma, which are microorganisms that outcompete all types of fungal infections, including bud rot and powdery mildew. Or you can simply use a citric acid and water solution, which will change the pH of your leaf surface, inhibiting its growth.

If you have bud rot you need to be careful when treating your plants.  Carefully cover the moldy parts of the plant with paper towels soaked in hydrogen peroxide. The spores are tiny and can spread easily. 

Using bleached tools, cut the covered infected area into a paper bag. Burn or throw away infected plant material; do not compost. Remove any decaying organic matter below the plant to reduce the spread, as spores can spread through air and water.

Unfortunately, once cannabis is moldy, there’s little you can do to salvage it safely. Consuming powdery mildew weed can be harmful, and trying to clean or treat it yourself will not remove all the spores. Discard any moldy cannabis to avoid health risks.

FAQs About Marijuana Mold

What does mold on pot plants look like?

Mold on pot plants can appear as white, gray, or black powdery spots or fuzzy patches on the leaves, stems, or buds.

Can you clean moldy weed?

No, cleaning moldy weed is not recommended as it may not remove all mold spores, posing health risks.

How does white powdery mildew affect cannabis?

White powdery mildew appears as a white, powdery mold leaves and buds, affecting the plant’s health and reducing yield and potency. In extreme cases, you can find weed covered in white powder.

What are the long-term effects of smoking moldy buds?

Long-term use of moldy marijuana can lead to chronic respiratory issues, infections, and exposure to mycotoxins, which may have serious health implications.

Understanding how to identify, prevent, and handle moldy weed ensures a safe and enjoyable experience for both growers and consumers. Always prioritize quality and safety with your cannabis use.