How to Prevent Mold During Post-Harvest Process of Cannabis

When you’re growing cannabis, you’re usually very meticulous and careful about the plant. You take every step to protect your cannabis plants from diseases and issues — like most growers. 

But there’s one mistake that you should avoid — thinking your buds are safe once they are off the plant. While your buds cannot get diseases after harvest, they can get one type of infection worse than you can imagine — mold. 

So, how do you prevent mold after harvest? In this guide, learn how to prevent mold during the curing and drying process. 

Where Does Mold Come From?

When your cannabis flowers are exposed to humid conditions, they can develop bud rot. This is a common mold, called Botrytis cinerea, which can develop on cannabis. Your cannabis plant may even get this mold when it’s still growing, but it’s not uncommon to find it on flowers during the curing and drying process. 

Here’s the thing, though; bud rot starts at the stem of the flowers and grows outward. So, it can be a bit difficult to spot mold until it’s usually too late. If you spot mold, you have already lost the flower. 

But what does it look like? Mold on cannabis buds appears as wispy or grayish-white in color, kind of like tiny fuzzy particles. Don’t confuse it with trichomes, though. Apart from that, your buds may also produce a sour or sweet smell that’s distinct from its usual aroma. 

When you spot mold on the buds, it may not look serious at first, but most of the damage is on the inside. Over time, the buds may even turn mushy and start losing their structure. Eventually, they’ll turn into wet, slimy plant matter. 

And don’t think that just because one cannabis bud is infected, the others are safe. Mold releases spores, which can get onto other buds and start infecting them, too. This is why it’s crucial to isolate and discard the infected buds before they start infecting others around. 

Unfortunately, the only way to deal with mold is to discard the buds. You can’t cure it. Also, don’t smoke the buds. Moldy buds can be hazardous, leading to various conditions like breathing issues, lung infections, and much more. So, when it comes to mold, prevention should be your priority. 

Types of Mold Commonly Found on Cannabis Buds

Here are some of the types of molds that can invade cannabis buds. 

1. Botrytis (Gray Mold)

Gray mold, scientifically known as Botrytis cinerea, is a widespread and harmful fungus that affects various plant species, including cannabis. This mold is particularly troublesome as it can infect plants at various growing stages starting from seedlings to mature plants and thrives in cool and damp environments. Botrytis spores spread easily through wind, water, and physical contact, so it's very challenging to control it. In cannabis plants, gray mold often appears as a grayish-brown coating on the buds, impacting the quality and yield.

Symptoms

Identifying Botrytis infection in cannabis is relatively straightforward due to some symptoms that are visible pretty easily. The main sign is the presence of brown or gray fuzzy or powdery mold on the surface of the buds. 

Botrytis, as mentioned earlier, starts at the core of buds leading to their decay from within. Affected buds might become soft, slimy, and discolored eventually and even change colors from brown or black as the infection progresses. 

The infection typically initiates in one section of the bud and then spreads outward, affecting other parts of the plant if you don't manage it properly. 

Besides affecting buds, Botrytis can also impact leaves by causing water-soaked spots that later turn brown and necrotic. These spots may merge together, resulting in leaf damage.

Sometimes, Botrytis can infect the stems as well. Eventually, the stems become weak and fall, significantly affecting the yields. 

2. Powdery Mildew

Powdery mildew is a disease that affects not just cannabis but a variety of other plants as well. However, ask any grower and they'll tell you it's a common culprit affecting cannabis plants. 

Powdery mildew, unlike other types of mold, can thrive even if there isn't enough water, which makes it particularly troublesome. It loves warm environments but can also survive in cooler climates with the right humidity levels. Powdery mildew typically appears as a powdery gray substance that mainly forms on the leaves, stems, and buds of cannabis plants.

Symptoms

The symptoms of powdery mildew on cannabis plants are unique and progress over time. 

The first indicators usually manifest as small circular white or gray powdery spots on the surfaces of the leaves, stems, and buds. These spots gradually enlarge and eventually cover larger areas of the plant. Leaves may look as if they are dusted with flour. 

As the infection advances, affected leaves might curl, twist, turn yellow, and eventually lead to tissue death. Infected buds and leaves could become deformed or stunted, hindering plant growth and reducing yield and quality.

Severe infestations can result in bud rot where infected buds turn brown and dry out. To effectively control and prevent powdery mildew, you should prevent factors that promote its growth. Needless to say, you should monitor it regularly and respond quickly as soon as you see any signs of infection to keep plants healthy and ensure a great harvest.

3. Aspergillus

Aspergillus is a type of mold that can grow on organic matter, including cannabis. It can display several colors like yellow, black, green, yellow, or black, based on the type of its species. What makes this mold very sinister is that it can adapt to many types of environments and conditions. Its spores are widespread in soil, air, and decaying plant matter and can easily contaminate plants if you don't control it. 

Symptoms

Fortunately, it's easy to detect this mold on cannabis as it's easily visible. Infected buds may show patches of mold in various colors. If the mold occurs when the plants are growing, it typically starts small but spreads quickly if you don't manage it. 

Keep in mind that even the plants can change color and turn dark when they are affected by this mold. There's no choice other than throwing away affected buds post-harvest, but if you somehow miss it, you'll see that the buds become dry and crumble easily. 

Health Risks

Aspergillus presents health risks mainly because certain types produce aflatoxins which are some of the most powerful known carcinogens. Aflatoxins are toxic metabolites that affect cannabis buds, but they can harm you too if you accidentally ingest or inhale it. 

For instance, inhaling Aspergillus spores can cause issues for people with weakened immune systems. Prolonged exposure to these spores can lead to conditions like aspergillosis — a lung infection.

Even individuals without health issues may experience reactions from exposure to Aspergillus spores. Symptoms such as coughing, wheezing, and difficulty breathing could occur.

4. Penicillium

Penicillium is a group of molds that can impact several types of organic substances, and cannabis is no exception. As it appears blue or green usually, you can recognize it easily. In addition, it looks a bit fuzzy, making it easier to not confuse it with resin.

Penicillium typically loves environments with high humidity, and since the area you're drying the buds will be humid, it's easy for this mold to attack the buds. The spores of Penicillium are widespread in the environment, so it's crucial that you prevent it in the first place. 

Symptoms

As mentioned, the signs are apparent, but you should be vigilant. 

First off, the affected buds display noticeable blue or green mold. Initially, as always, it starts small but spreads across the entire bud if you don't control it. As the infection advances, the affected buds may start decaying and it could also become completely unusable after a while. 

Apart from the obvious discoloration where the buds look somewhat dark, they may also smell musty, which is a surefire sign of mold. 

Health Hazards

Penicillium presents health risks primarily because some species produce mycotoxins. These are toxic substances that can lead to several health issues ranging from allergic reactions to severe illnesses. Not only can you suffer from respiratory problems after inhaling it but the spores may also induce allergic reactions in some people, leading to itchy eyes and skin rashes. 

How to Protect Your Buds From Mold During the Drying Process?

During the drying process, you can use a few methods to ensure your cannabis buds don’t get moldy. Usually, this involves maintaining the right temperature, humidity, and air circulation. 

When you harvest the buds, they have very high moisture content. This makes them difficult to smoke, which is why you dry your buds to bring the water content down to 10-15%. Additionally, this excess water can also make the buds susceptible to mold. It loves humidity. 

So, follow the regular drying process, as usual. It’s a straightforward process. All you need to do is hang your cannabis buds from a string, upside down, in a dry and dark place with good air circulation.

You may use a designated drying room, closet, or cupboard for it, and if the space is limited, cardboard boxes can also come in handy. As long as they have holes for the air to move around. 

But you need to go a step further and be more meticulous if your buds are susceptible to mold. How do you do that?

Create an Ideal Environment 

Maintain the right relative humidity. Ideally, you should dry your cannabis flowers at 50°F to 68°F (10°C to 20°C) with a relative humidity of 50-60%. Some growers even recommend keeping the temperatures a bit higher in the initial three days to speed up the drying process before lowering it down. 

You’ll know the buds are dried and ready for curing when you can snap the stems easily, which usually takes around two weeks, based on the drying conditions. If the weather in your house is too hot, you should use an air conditioner to dry out the buds. 

Keep in mind that air circulation is vital in preventing moisture buildup that can foster mold growth. Stagnant air can trap moisture and the buds can develop mold easily. 

To prevent this, implement ventilation in not just the growing areas but in the drying and storage areas as well. Ensure ventilation with exhaust and intake fans to promote air circulation and maintain airflow throughout the area.

You can also use oscillating fans to disperse air around drying buds. Finally, avoid overcrowding as it can hinder airflow and lead to increased humidity levels near the buds. When drying, use drying racks that allow space between buds for air circulation.

How to Prevent Mold During the Curing Process?

THe buds in this pic do not have mold. However, once the buds are dry, you should follow that up by curing them in airtight mason jars for a few weeks. As the bud cures, they lose even more moisture, however, it will be at a slower rate, and this brings out the flavors and aromas of the buds while purging impurities. 

However, moisture can still build up in the jars. And like you already know, a moist environment is a breeding ground for mold to form. So, you need to take certain steps to ensure your buds don’t develop mold during this time. Here are some tips for it. 

• Keep Them Trimmed Up 

Before you even start the curing process, it’s a good idea to trim your buds properly. Old plant matter like leaves and stems can hold moisture, making it easier for mold to appear. So, when you trim the buds, whether dry or wet, you ensure your buds don’t have any of those unnecessary pieces. 

• Maintain Cleanliness

Here, cleanliness is crucial, too, to protect the buds from mold. Mold spores are everywhere in the environment, so any slight neglect of cleanliness can result in contamination. Regularly cleaning and sanitizing all your tools and facilities helps reduce the presence of these spores, lowering the risk of mold growth.

This includes tools you use during harvesting, drying, and curing. For example, clean your scissors and trimmers with alcohol or other disinfectants before and after each use.

Make sure to clean and sanitize drying racks, shelves, and all surfaces where cannabis buds are dried. Also, your curing jars should be clean and dry before storing the buds in them. Using airtight containers will make your life easier as it prevents moisture and mold growth. 

In addition, clean the floors, walls, and ceilings of the room where you dry the buds to avoid dust, and debris and prevent the spores from accumulating. 

• Again, Fix the Environment 

Speaking of the environment, the best humidity levels for curing cannabis are between 58-65%. If your buds are wet, it is a sign that the humidity is above 70%. In that case, pour them out and dry them for around two hours before returning them to the jar. If the buds feel moist, leave the jars open for four hours. 

• Don’t Forget to Burp

During the curing process, the buds release moisture, which breaks down chlorophyll. But this moisture being trapped in the jars can also lead to mold. So, burping the jars is crucial at this stage to let off the excess moisture. 

Usually, you want to burp your cannabis jars two to four times daily during the initial stage of the curing process. As humidity levels drop, you can burp your jar less frequently — once a day, at least, though. 

• Keep an Eye Out 

You should also regularly keep an eye on the buds for any sign of mold like discoloration, spots, or fuzzy growth. Pay attention to any unusual odors as they could be a warning sign. Frequently check the buds for mold and remove any affected buds immediately. Remember, vigilance is the best way to protect your buds against mold. 

Please don't skip this step as you'll avoid various issues if you just take the time to inspect the buds after every stage to ensure they aren't affected by mold of any kind. You can also implement a sorting process to segregate healthy buds from those displaying signs of mold.  

• Invest in a Hygrometer and Dehumidifier

If you’re serious about growing cannabis, a hygrometer is an indispensable tool for measuring the exact humidity levels of a space. It helps you check the humidity levels, so you can maintain the right relative humidity at all times. 

If you find the humidity to be too high, you can then invest in a dehumidifier to bring down the humidity. This ensures your buds dry properly, preventing the risk of mold. 

Protecting your cannabis buds from mold takes effort and consistency. 

Store Your Buds Well

Just because your buds are cured doesn’t mean they are safe from mold. They can still catch mold if they are incorrectly stored. So, here are some tips for storing your buds. 

• Use Humidity Packs 

The easiest way to store your buds is in mason jars with humidity packs in them. These packs help absorb excess moisture and maintain a consistent humidity level within the jar. By doing so, they create an ideal environment that preserves the freshness and potency of your cannabis.

Humidity packs are specifically designed to regulate the relative humidity, ensuring it stays within the optimal range for cannabis storage. This prevents your buds from drying out too much or becoming too moist, both of which can affect their quality. Using these packs, you can extend the shelf life of your cannabis while keeping its flavor and aroma intact.

• Freeze the Buds 

If you want to store your buds for longer, you can even freeze them. Mold does not survive in cold temperatures, so freezing is a good option. 

However, do note that many enthusiasts are against the idea of freezing cannabis buds. Freezing temperatures can separate the trichomes from the buds, reducing their quality, potency, and flavor over time. Freezing can also make them harsh to smoke. 

• Humidity Control Bags 

You can also splurge on some humidity-control bags that are specifically designed for storing cannabis. Cigar boxes can also come in handy here as they work on a similar principle of controlling humidity. 

Summary: How to Prevent Mold During Post-Harvest Process?

Preventing mold is an ongoing process that requires attention to detail and vigilance — like Batman. So, start by maintaining proper humidity levels, trimming and cleaning your buds properly, and investing in the right tools. 

With the tips mentioned above, you can easily protect your cannabis buds from mold every step of the way. In the end, you’ll be rewarded with buds that are not only free of mold but also cured and dried in ideal conditions. In other words, your buds will taste sweeter than ever!