The 5 Best Ways To Check For Moldy Weed, Plus How To Avoid It

Master Growers Are Pulling $120k Yearly and so can YOU Enroll Now Enter Code: BWS20 For A Special Bonus Discount.

marijuana leaf

Nothing kills a buzz like moldy weed. It affects the potency, the smell, and the flavor of your favorite strain — and not in a good way.

Enter Discount Code: 20AS-661091 and get up to 30% off your ENTIRE seed order + free seeds Buy Seeds Here

Moldy weed can even cause some rather serious health problems, so it’s vital to know how to check your bud for rot and what to do if you find it.

In this article, the cannabis experts at Honest Marijuana tell you everything you need to know about moldy weed and give you tips on how to prevent mold growth in the first place.

How Does Mold Affect Your Health?

The two most common types of marijuana mold are:

  • Botrytis cinerea (a.k.a. bud rot)
  • Aspergillus

Bud rot is the least dangerous of the two, although it can still cause serious health problems, like lung damage.

Inhaling aspergillus, on the other hand, can cause infection, aspergilloma (ranging from cough to severe fatigue to bleeding airway), and even invasive pulmonary aspergillosis, which can be fatal if not treated properly.

Avoid both of these molds at all costs. The first step in keeping yourself safe is knowing what causes mold to grow.

What Causes Moldy Weed?


Mold, like most other organisms, needs oxygen to survive. But you can’t grow and store cannabis in a vacuum. That just won’t work.

You could try vacuum sealing your weed for long-term storage, but that’s definitely not convenient if you want to use those buds in the near future.

Instead, don’t worry too much about oxygen, and focus your efforts on the next cause of moldy weed.

High Humidity

Humidity is the number one cause of mold growth on marijuana plants.

As soon as the humidity around your pot plant passes a certain level (63 percent), mold can start to grow. All it needs is that moisture and a bit of oxygen and it’s off to the races.

Mold doesn’t even require light to grow — just oxygen and water. So you can store your pot in the deepest, darkest dungeon, but if there’s oxygen and high humidity, you’ll end up with moldy weed.

Lack Of Airflow

Mold spores thrive in tight conditions with low airflow.

In outdoor grow operations, the wind usually provides enough airflow to keep mold at bay. In indoor grow operations, fans keep the air circulating and prevent mold from taking hold.

When storing your weed — which is when most mold begins to grow — it’s essential to crack the lid or open the bag at least once a day to replace the stale oxygen with new.

That’s not a problem if you’re partaking of the weed on a daily basis. The simple act of retrieving the bud for your next smoke sesh supplies enough airflow to keep your cannabis mold-free for a short time (assuming the humidity is low enough).


Temperature can also affect mold growth, but this variable is much more difficult to control because mold flourishes in the same range as humans.

If you want to ensure that mold won’t grow, you can keep the temperature around your weed below 40℉ or above 100℉. Is this realistic, though? No.

Sure, mold won’t grow, but both extreme cold and high heat will damage your cannabis buds in other ways.

A Note About Light

Astute readers will notice two seemingly contradictory facts throughout this article:

  1. Mold doesn’t need light to grow
  2. We recommend storing your weed in a dark place

What’s up with that? Well, light is basically heat.

You can control the ambient (a.k.a. surrounding) temperature of the space where you store your weed containers, but it’s extremely difficult to control the temperature inside those containers.

Even if you store your weed on your kitchen counter (e.g., in the sun) and you maintain a constant ambient of 70℉, light is going to raise the temperature inside that container by at least several degrees (if not more).

Those several degrees can quickly push the temperature of your weed into the mold-growing zone without you even knowing it.

Unless you have some seriously high-tech storage devices that maintain their own internal environment, it’s best to store your weed in a cupboard or closet away from direct sunlight — not because mold needs light to grow, but because it needs the right temperature.

What Are The Best Ways To Check For Moldy Weed?

moldy weed

1) Look

The easiest way to check for moldy weed is to examine the bud with your naked eye. Common signs of mold include:

  • Cobweb-like material
  • Powdery appearance
  • Dark spots on green buds
  • Yellow fuzz
  • Grey fuzz
  • Slime

If you see any of these on your pot plant, consider it moldy.

2) Smell

Your weed will exhibit a wide variety of aromas — from berry to diesel fuel to skunk. But if you smell sweat or urine, your bud is probably going moldy.

That said, some people have more sensitive sniffers and will smell more of the weed fragrance even if mold is present. Additionally, some molds don’t produce any aroma until they’re further along in their development.

3) Feel

Healthy marijuana that is properly cured should feel dry and crispy. If your weed feels damp or spongy, it may be moldy.

Detecting mold on your marijuana takes practice and often involves all three of the tests above — look, smell, and feel.

But if you really want to be sure you don’t have moldy weed, you can take your tests to the next level by looking deeper and checking for recalls.

4) Look Deeper

If you own a microscope or can get your hands on one (they’re fairly cheap now), you can detect the first traces of mold before it becomes visible to the naked eye.

Even a jeweler’s loop or a strong magnifying glass can help you look deeper at the surface of your ganja flowers.

Mold produces structures (i.e., hyphae) that look nothing like any other part of the pot plant. If you see something out of the ordinary, it could be mold.

5) Check For Recalls

As a last resort, you can check media outlets and even the grower’s website (if they have one) to check for recalls due to moldy weed.

This may not be the most reliable way to check for moldy weed — because many issues like this go unreported — but it can be effective if the crop was large enough and shipped to multiple locations.

Will Moldy Weed Get You High?

Neon spirals

The simple answer is…maybe — and only if you use a THC strain. If you use a high-CBD strain, you won’t get high at all because only THC creates a psychedelic effect.

And even then, whether or not you get high off your moldy weed depends on a number of factors, including:

  • Your body composition
  • Your tolerance to THC
  • The amount of marijuana you use
  • How you use the moldy weed (e.g., smoking, eating, drinking, etc.)
  • The quality of the cannabis plant from which your buds came
  • The THC percentage in the original plant

For more information on how these factors affect your cannabis experience, check out these article from the Honest Marijuana blog:

Whether your intentions are recreational or medicinal, you really want to think twice (and even three or four times) before partaking of moldy weed.

Once you actually see the mold, it’s probably pretty prevalent throughout the plant. This is very much like moldy bread: once you see the green, blue, or purple splotches on the surface, the mildew has spread throughout the loaf.

Even if you cut off the surface discoloration, making a PB&J with this bread would be a really bad idea.

Similarly, it’s hard to get rid of ALL the mold once you start seeing it on your cannabis plants and flowers, so even if you dispose of obviously-infected buds, there may be some hiding elsewhere that you can’t see with your naked eye.

It’s best to dispose of the moldy weed and start saving up for another batch.

That said, if you want to try salvaging moldy weed, here are some suggestions for the right way to go about it.

What Should You Do With Moldy Weed?

Arms of people passing a joint after checking that the weed wasn't moldy

The only 100-percent safe way to “use” moldy weed is to get rid of it. Sorry.

But if you want to try recovering the plant matter for recreational or medicinal use, check out the first three suggestions below.


Decarboxylating moldy weed in your oven (instead of smoking it) can be an effective way of getting rid of the mold.

Most molds can’t survive above 140℉, so baking the plant matter in a 230℉ oven for 35 minutes is a great way to render the mold inactive.

From there, you can cook a batch of edibles or even try a concentrate.

Whip Up A Batch Of Concentrate

Once you’ve decarbed your weed, you can brew your own concentrate at home.

The chemicals (e.g., alcohol, butane, and others) kill most of what mold remains after the decarboxylation process and make your cannabis flowers useful again

Use A Water Pipe To Filter The Mold

When your dabs are ready to go, load them in a dab rig with a water filter at the bottom. Liquid can filter out up to 15 percent of the mold on a pot plant.

If you’ve run your moldy weed through a decarb process and then cooked up an extract with it, inhaling the vapor through a water filter should remove any trace amounts of mold still in the mix.

But it’s worth saying again: the only 100-percent safe way to “use” moldy weed is to get rid of it by recycling it as compost.


If you discover mold on your marijuana, consider recycling it as compost.

Proper composting raises the temperature of the soil to around 170℉. This high temperature kills the mold and breaks down the plant matter so you can use it as soil for the next generation of cannabis plants.

If your compost doesn’t reach 140℉ to 170℉, the mold may survive and transfer to the new plant you’re trying to grow.

How To Avoid Moldy Weed

example of moldy weed plant matter

If you grow your own weed, the best way to avoid mold is to grow, cure, and store it in the proper conditions. Temperature, light, and humidity are your three biggest concerns.

Avoid Moldy Weed While Growing

Relative humidity (usually abbreviated RH%) affects everything from how well your plants break down chlorophyll to how much THC and how many terpenes they produce.

But, as we’ve mentioned repeatedly in this article, that same humidity is also a major contributor to moldy weed.

So what’s an at-home ganja grower to do? Control the crap out of the humidity.

1) Maintain A Strict RH% Level

If you’re growing your plants outside, there’s not much you can do to control the humidity — you’re at the mercy of mother nature.

But, if you nurture your cannabis in a greenhouse or indoor operation, you can take steps to maintain the right humidity at all times with both a humidifier and a dehumidifier.

Marijuana plants thrive in humidity levels between 40 and 50%.

If the RH% falls below 40%, use the humidifier to pump a little more moisture into the air. If the RH% rises above 50%, use the dehumidifier to pull a little moisture out of the air.

2) Keep The Air Moving

Another way to prevent moldy weed is to ensure plenty of airflow.

Molds such as Botrytis cinerea and Aspergillus absolutely love stagnant (still) air. Installing a few fans is an easy way to keep the air moving around your growing plants.

Maintaining a strict RH% and ensuring plenty of airflow will also help prevent such destructive pests as cannabis aphids.

For more helpful information on growing healthy, non-moldy weed, check out these articles from the HMJ blog:

And be sure to take note of these guides from the HMJ main site:

Avoid Moldy Weed While Storing

Jars of non moldy weed
1) Choose The Right Containers

Marijuana packaging has come a long way in the hundred or so years since the first pharmaceutical companies and pharmacists started selling and distributing cannabis in the United States.

Back then (and we’re talking the late 1800s/early 1900s), it was mostly tin cans and ceramic pots.

Nowadays, most serious stoners avoid moldy weed by storing their pot in airtight homesteading-style glass mason jars.

If you’re not familiar with glass canning jars, they’re the containers commonly used for preserving fruit and pickling vegetables. You can pick up a case for cheap at your local hardware or grocery store.

A glass canning jar with a lid is perfect for pot since mason jars are impermeable to oxygen, aren’t affected by residual humidity, and are inert to temperature fluctuations.

When you store your cannabis in a glass canning jar, you can rest easy that it isn’t the container that’s causing your moldy weed.

In addition, glass doesn’t secrete any chemical compounds that will kill the fresh aroma of your cannabis terpenes.

Unfortunately, most clear mason jars won’t protect your ganja from becoming moldy or dry and brittle due to sunlight or heat damage. That’s why opaque or dark, tinted glass jars are always your best bet.

If you can’t find a glass container with a lid, an airtight container made of titanium is your next best option to preserve your pot since it handles heat pretty well, keeps air and light out, and doesn’t secrete any ganja-ruining gases.

It’s also very important to make sure that your jars are the right size for the amount of ganja that you want to store since empty jar space is a prime environment for unwanted heat, ambient humidity, and airborne mold and mildew. You don’t want any of that stuff coming in contact with your herb!

You can also vacuum seal your ganja jars to reduce the amount of oxygen you expose to your stash.

2) Choose The Right Location

To prevent mold from forming, store your weed in a space with the following characteristics:

  • No direct sunlight
  • Temperature below 75℉
  • Humidity between 59 percent and 63 percent

A closet or small room with the right climate and humidity controls is ideal for this type of storage.

Whether you use a glass jar or some other container, it’s critical that you store your herb in a cool, dark, dry place, such as a:

  • Cupboard
  • Cabinet
  • Drawer

If none of those options are available, try placing your ganja jar in a dark paper bag. Doing so can help protect your cannabis from harmful light and UV rays that can all but wreck the buds for future use.

Tips To Keep Your Weed Fresh

grower checking for moldy weed
1) Cover That Stuff

Never leave your medicine out in the open on tables or countertops exposed to light, heat, and/or humidity.

2) Stay Cool But Not Too Cool

Never store your stash near electronics or other heat-generating gadgets since the heat will degrade your dope.

Never store your reefer in the refrigerator. The temperature fluctuations from opening and closing your fridge door every time you get the munchies will make your marijuana moldy and mildewy.

And never keep your cannabis on ice in your freezer since this will break trichome resin heads off from the rest of the reefer before you can consume it.

3) Preserve The Original Flavor And Aroma

Never, ever add fruit peels to flavor your weed even if some sources tell you this is ok. Doing so will add unwanted moisture, mold, and mildew into your marijuana.

Similarly, never store your weed in direct contact with any other substance with a strong aroma, such as:

  • Makeup
  • Perfume
  • Cologne
  • Deodorant
  • Shaving cream
  • Aftershave
  • Paint
  • Polish

We’re not sure why you’d do this in the first place, but exposing your ganja to any commonly-carried cosmetic can result in tainted flavor and aroma.

This is also why you want to store your stash separately from your lighters, pipes, bongs, grinders, pokers, and other pot paraphernalia. Those items will get funky with use and overpower the freshness of the pot you are aiming to preserve.

4) Don’t Put Your Faith In Plastic

Plastic, especially plastic sandwich baggies, is positively the worst way to prevent moldy weed. Plastic baggies do absolutely nothing to keep light, air, heat, cold, or moisture out of your marijuana.

Even sealable plastic baggies won’t keep your marijuana fresh. Sealable plastic baggies are actually permeable in many ways and will let all the bad stuff in and all the good smells (or telltale smells, depending on how you look at it) out from your buds.

And, to make matters worse, plastic is a horrible material for keeping pot fresh because it has a static charge that will pull precious trichomes from the plant matter onto the plastic, creating a fine, sticky, powdery mess that you’ll never be able to get out of the bag into your bong.

5) Keep ‘Em Separated

When deciding how to store your weed, it’s vital that you keep different strains of weed separate.

This helps to preserve each strain’s individual aromas and psychoactive effects, and won’t spread mold from one plant to the next.

In addition, some strains are more resistant to mold than others. So, while strain X has a tendency to get moldy pretty quickly, strain Y may go weeks or longer without the faintest hint of contamination.

But, if you store X and Y together in the same container, once X does start to sprout, you can pretty much guarantee that Y will be moldy weed in short order.

Even with your best efforts, though, mold may grow on your bud. The only surefire way to avoid moldy weed is to purchase it in a special container.

The Best Way To Avoid Moldy Weed

Honest Marijuana cannabis container

Honest Marijuana packages and seals their marijuana flowers in airtight, light-proof, humidity-proof canisters that keep the bud at just the right conditions to prevent mold from forming and growing.

We even take it a step further to ensure that there’s zero chance for mold to flourish. What do we do? We get rid of the oxygen in the canister and replace it with nitrogen.

Mold can’t grow without oxygen, so by controlling this final variable, we can provide you with the purest, safest cannabis on the market today.

You can rest assured that there’s no trace of mold on your marijuana — and won’t be for a long time — when you buy your ganja from Honest Marijuana.

For more information on all things cannabis and to check out our 100-percent all-natural marijuana products, visit today.

The post The 5 Best Ways To Check For Moldy Weed, Plus How To Avoid It appeared first on Honest Marijuana.

Please Share This: