weed dry box

How to Avoid Mouldy Weed During Drying and Curing

Ahhh, harvest time! It’s easily the most exciting time on your calendar. Unfortunately, a tiny little mould spore can ruin all your hard work if you’re not careful. In this article, we’ll show you how to avoid mould while drying, curing and storing your weed, so you can enjoy your buds safely.

Don’t let your guard down after harvest—learn how to protect your buds from mould during the final stages of the growing process.


What Makes Cannabis Buds Mouldy?

The mould that can develop on cannabis flowers, colloquially called “bud rot” by growers, is caused by Botrytis cinerea, a necrotrophic fungus that also grows on grapes, strawberries, tomatoes, and other fruits and vegetables.

Botrytis thrives in warm, humid climates and attacks the living cells of plants or fruit, while feeding on the dead matter. It develops on the stems of live cannabis plants or harvested flowers and slowly grows outwards, which makes it particularly hard to spot. Usually, by the time you spot botrytis on the surface of a bud, it will have almost completely destroyed its insides, leaving it wet, slimy, and smelly.

How to Prevent Mould after Harvest

In the grow room, the principles of preventing mould are maintaining optimal temperature and relative humidity, as well as proper air circulation. Post-harvest, you’ll want to follow the exact same principles to avoid losing your hard-earned buds to mould.


Cannabis flowers have a high water content when they are harvested. Therefore, before you light up your buds, you need to be patient and let them dry till they contain only about 10–15% of water.

Drying your buds is as simple as hanging them upside down from a piece of string or clothesline. Where you hang them is completely up to you, just make sure they are in a dry, dark place where the air circulates freely. Growers typically dry their buds in a designated room or a cupboard/closet. If you’re short on space, you can even hang your buds inside a cardboard box; just make sure to poke some holes in the box for the air to circulate.

Creating the Perfect Drying Environment

Ideally, you’ll want to dry your buds at 18–20°C and 50–60% relative humidity. Some growers like to keep the temperature at the higher end of the spectrum during the first 3 days to dry their buds a little faster, before drawing the temperature back down to slow the process. You’ll know your buds are ready to be cured once their stems snap easily. This can take up to 2 weeks, but it will vary depending on the temperatures and humidity levels you’re drying your flowers at.

If it’s hot, we recommend drying your buds in a lightly air-conditioned room. You can also use air-conditioning to drive down the humidity if you live in a particularly humid area. Finally, remember to use fans to circulate the air around your buds to dry them evenly and further prevent mould from forming.


Once your buds are nice and dry, you’ll want to cure them in airtight jars for at least 2–3 weeks (or more, if you have the patience).

As buds cure, they continue to lose moisture, but at a much slower rate. This slow release of moisture helps bring out the aromas and flavours in your flowers and also purges any impurities. Unfortunately, the build-up of moisture inside your curing jars can also create the perfect conditions for botrytis spores to grow.

Trim Like a Pro and Keep Things Clean

Before you cure your buds, you must ensure they’ve been trimmed to perfection. Old foliage like leaves and stems can trap humidity and create the ideal environment for mould. Whether you prefer trimming wet or dry, make sure your harvested flowers are free of unnecessary plant matter before you pack them into your curing jars.

Another key step to preventing mould when curing weed is cleanliness. Make sure your jars are sterile and dry before you start filling them with flowers. Also, only fill your jars to 3/4 of their capacity. Keep your jars in a cool, dry, and dark place (light degrades THC and can drive down the potency of your buds).

The Art of Burping

To further prevent mould when curing weed, we recommend you open (or “burp”) your jars 2–4 times a day to remove and replace the old, humid air. After about 1 week, you can start burping your jars less frequently (1–2 times per day), as the flowers will be dryer and release less moisture.

If you’re worried you’ll forget to burp your jars (or you’re lucky enough to have a huge harvest on your hands), you can use humidity packs to control moisture levels inside your jars. For curing cannabis, we recommend using packs that help maintain 62% humidity.

Keep a Watchful Eye

Finally, the best protection against mould is a keen eye. Make sure to regularly inspect your buds during the curing process. If you suspect some of your buds to be developing mould, separate them from the rest as quickly as possible to avoid the fungus spreading even further.


Once you’ve cured your weed for at least 2–3 weeks, it’s officially ready to be smoked. You can continue storing your flowers in your curing jars, using humidity packs to avoid them drying out too much over time and to maintain humidity inside the jars at optimal level. Remember that your buds will continue curing and their flavours should intensify as they mature, so don’t smoke your way through the stash too quickly!

Keeping Mould at Bay—Bottom Line

It’s vital that you don’t rush your way through the final stages of the growing process. While we know you’ll be anxious to sample your home-grown buds, taking the time to properly trim, dry, and cure your flowers will take them to the next level in terms of flavour, aroma, and potency, all the while keeping them safe from mould.

And if you do find buds that are affected by the dreaded fungus, make sure you remove them and closely inspect the rest, as smoking mouldy weed is dangerous for your body!

Humidity Packs Protect Against Mould

Humidity packs are small and simple tools that pull in moisture from the surrounding environment. When the moisture level starts to climb, they’ll absorb water particles that would otherwise serve as a breeding ground for mould.

Moisture Fighters Offer Two-Way Control

At Royal Queen Seeds, we engineered our own humidity packs specifically for curing cannabis buds. Our Moisture Fighters possess a two-way control mechanism that allows them to both trap and release moisture. This enables them to take in excess moisture while also preventing your flowers from becoming too dry and losing their flavour.

Humidity Control Pack

A Plant-Based Product With No Preservatives

Our Moisture Fighters are crafted with the health of the environment and your buds in mind. Each packet derives entirely from plant-based materials and contains absolutely zero preservatives. You don’t have to worry about any unwanted chemicals leaching out and contaminating your pristine organic flowers.

Humidity Indicators Keep You Informed

Moisture Fighters remove any guesswork from the curing process. Each pack features a card that houses a humidity indicator. This reusable piece of kit will let you know when you need to swap out your Moisture Fighters. Knowing exactly when to do this means you’ll keep the curing environment perfect during the entire process.

How to Use Moisture Fighters

Moisture Fighters are extremely easy to use. Keep your flowers juicy and terpene-rich using the steps below.

  1. Remove Moisture Fighters from their packaging, making sure not to open the Fighter itself.
  2. Place a Moisture Fighter and the humidity indicator alongside your buds in their curing jar.
  3. Let the Fighter do its thing. When the dot on the humidity card turns from pink to blue, swap out the Humidity Fighter for a fresh one.
  4. Reset the reusable indicator back to the pink setting to keep track of the new Fighter.

Afraid of losing your precious buds to mould? Click and read everything you need to know on preventing mould when drying and curing cannabis flowers.

Curing and Drying Cannabis in a Few Simple Steps

Drying weed might appear simple but in reality it is not that easy. A lot of people make mistakes during this phase of the cultivation. It’s possible to do lots of things wrong when drying and curing weed. Yes, admit it. What’s worse than sweating for weeks and then messing it all up in the final phase. In this article we explain how to dry and cure weed quickly – and properly.

Because drying and curing weed is a complicated subject, we cover the following points in this article:

  • When is Weed Ready for Cutting and Drying?
  • Factoids, Rules of Play and Ideal Conditions
  • Drying Weed Quickly – But Not Artificially
  • Different Drying Techniques – Drying Weed in a Number of Steps
  • How Long should Weed Dry
  • Curing Weed after Drying
  • Storing Weed

When is Weed Ready for Cutting and Drying?

Before proceeding to dry your weed, it’s vital to harvest and cut it at the right time. To figure out the perfect timing, you need to keep looking carefully in the final weeks at the trichomes on your weed. These are the white or brownish resin glands on the buds. To distinguish these with the naked eye you have to look really hard. A Trichoscope is a handy tool for this. This is a convenient pocket microscope with which to keep a close eye on everything.

Always keep in mind: observation is the basis for a good harvest. You can tell by the trichomes/resin glands when it’s time to cut and dry. For more information read our blog. ‘How and When to Harvest Weed‘.

Factoids, Rules of Play and Ideal Conditions

There are a number of things to consider when you intend to dry weed. Hence this list so that you don’t get any surprises. Every cultivator who wants good quality cannabis must adhere to these rules of play. So please read carefully:

    Keep in mind that you will lose some 65 to 80% by weight when you dry your weed. 65% loss by weight is something to be happy about. This doesn’t happen very often.

It is also the case that after growing and flowering, weed can go on to develop mould.You can prevent this by carefully reading through the remaining points in this list.

Very important: darkness. It would be a shame if your weed lost some of its potency, wouldn’t it? For that reason, always dry it in a dark place. Light breaks down THC and that would be a pity.

For the first few days at least, drying weed will produce an enormous odour of weed.Do you want to do your neighbours a favour? Then buy a carbon filter. They are universally available and you’ll be doing a favour not only for your neighbours but for yourself as well. Masking the odour of weed? Then buy a carbon filter.

The ideal temperature for drying weed is between 17 and 21 degrees Celsius. We recommend you keep the temperature at around 20 degrees Celsius for the first 3 to 4 days, and then switch to the slightly lower temperature. This will give not just the moisture but also other substances in your cannabis the opportunity to dry out / vapourize. In any event, make sure the temperature does not go above 21 degrees Celsius.

The ideal humidity for drying cannabis is around the 50% mark. This prevents your weed from drying out too much and denies mould the opportunity of forming. It can be tricky to keep the humidity at the right level. Useful tools for this are humidifiers and hygrometers. These can be found all over the Internet or purchased in many shops. Are you going to dry a large quantity? Then we strongly recommend you buy one. The wrong humidity will do more damage than you’d like. Dessication, mould and other nasty things could be the result.

Give your buds enough space. They like to be hung up rather than laid down. In this way they have a larger drying surface, the air can do its work at every part of the buds and you avoid moisture spreading from one bud to another. Moreover, you give mould no opportunity.

  • Good ventilation is vital. Fresh air is necessary to allow cannabis to dry off as ‘freshly as possible’. By providing the drying area with fresh air, you stop mould getting the chance to cause damage to your lovely green buds. But don’t let the fan blow out its air directly onto the weed. Artificial drying techniques are bad for the quality of the weed.
  • Drying Weed Quickly – But Not Artificially

    The Internet is inundated with growers looking for ways of drying weed quickly. But the fact is: if you want to get the best quality weed, you can only achieve this by striving for the perfect conditions. It’s often the case that the longer the process takes, the better the weed. Artificial means can get the weed to dry quickly but the green gold’s quality will go downhill. Things which you absolutely must not do:

    • Dry weed in the microwave
    • Dry weed with a hairdryer.
    • Dry weed in the oven or over the stove
    • There should be no direct wind present when drying

    Most of the things you shouldn’t do involve high temperatures. More will be lost at high temperatures than you would like. In addition, some of the substances in weed (such as chlorophyll) need more time to vapourize / dry off than water. Temperature is not involved in this. To make matters worse, your weed will also become much too dry. All this leads to the weed being less tasty and producing a tickle in the throat. In short: it may seem like a good idea to dry weed quickly but it isn’t. Let the microwave do what it’s supposed to and let nature take its course.

    Drying weed in the microwave is an absolute no-no

    Different Drying Techniques – Drying Weed in a Number of Steps

    There are several ways to dry weed. You can choose for yourself which one of the various drying techniques to use. It’s convenient to dry weed in a box if you’re only drying a small amount but if you have a large quantity it’s best to purchase a drying net. So make your choice by examining the quantity of weed you want to dry. We present the various drying techniques in a nutshell and explain what you need to do in a few steps.

    Drying Weed in a Box

    1. Use a large shoe box, packing box or some other type of box. This drying technique is suitable for up to approximately 75 grammes of weed (depending, of course, on the size of the box). Have you got more? Then you need a larger space. So choose a different technique.
    2. Make sure the shoe box is in a dark room at a temperature between 18 and 21 degrees and humidity around 50%.
    3. Make two holes in the sides of the box and run a string between. If it’s sufficiently large, you can run multiple strings next to each other. At all times ensure that there is sufficient space between the buds. They must not be touching each other, that’s a definite no-no.
    4. Ensure sufficient ventilation. You can do this by making more holes in the box. Please note: the humidity can rise quickly in a cardboard box. We recommend, particularly at the beginning, to open the box every day and check the conditions. This also provides the buds with some extra fresh air.

    Duration: 12 to 20 days.

    Drying Weed in a Growing Area

    1. Did you cultivate indoors? If so, the growing area is an excellent place for drying weed as quickly as possible. Provided, of course, that it’s dark there. So switch off the lamps.
    2. Make sure the temperature is between 18 and 21 degrees and the humidity around 50%. Before you start drying, check that there are no vermin or other creatures present in the room.
    3. Do you want to avoid nuisance from the odour of the weed? If so, we recommend you purchase and install a carbon filter.
    4. Ensure sufficient ventilation. Mount a fan to bring fresh air into the growing area. Please note: don’t put the fan right next to the weed.
    5. Run a number of strings across the growing area or buy a drying rack. Hang the buds upside down from the strings or in the rack. Ensure there is sufficient space between each bud.
    6. Check on the conditions every day. Also keep a good lookout for vermin or diseases. Creatures like spider mites, mealy bugs, aphids or similar can ruin the harvest all too quickly. For more information about these diseases read our blog ‘Critical Diseases‘.

    Duration: 10 to 18 days.

    Drying Net for weed

    1. Buy a drying net (readily obtainable on the Internet) and hang it up in a dark area. A drying net is especially suitable for drying weed because you can accommodate a large amount of buds in a relatively small space and still maintain enough air. Moreover, the drying process is faster than when you hang up in a box or growing area. Do you have a large quantity of cannabis? If so, then this drying technique is the one recommended.
    2. Make sure the temperature is between 18 and 21 degrees and the humidity around 50%.
    3. A drying net is made up of several layers. Spread your weed over the various layers, laying the buds slightly apart so that mould gets no opportunity to occur. Because the buds are laying rather than hanging, it’s advisable to turn them over from time to time.
    4. Ensure sufficient ventilation. If you use a fan, make sure that it’s not pointing directly at the drying net.
    5. Allow the drying net to do its work. Check each day that the conditions are still ideal, keep an eye out for vermin and allow the weed to dry slowly.

    Duration: 8 to 18 days.

    How Long does Weed have to Dry for?

    As you know from reading the above, the length of time weed has to dry for varies according to technique. We have made an estimate for the various techniques. We have based this on the experience of dozens of growers. All in all, drying weed takes between 8 and 20 days. As a general rule, the longer the weed has been dried, the better the end result. Though it can be shorter due to circumstances.

    Snap test

    ‘How Long does Weed have to Dry for?’ This is not an easy question to answer. But you can test whether your weed is properly dried! You do this by applying the ‘snap test’. Weed is really only properly dried if you can hear the stem/twig snap in one go. Is the twig still bendable? If so, the weed still needs more time to dry properly. It sounds too simple, doesn’t it. And yet this test is very reliable.

    Curing Weed after Drying

    If you thought that once your weed was dry, you could just relax on the sofa, you’re mistaken. For the best quality weed, it is necessary to let the weed cure. Curing weed is the hardening-off process which optimises its smell, taste and effect. You allow the cannabis to ‘ripen’, as it were. During this ripening process, bacteria get the chance to break down the remaining substances (such as chlorophyll). Furthermore, you can determine the ideal humidity for weed by drying at the correct air humidity.

    Curing weed professionally is a tricky business. In this process too, mould can still happen. So be sure to read the instructions carefully and regularly examine your valuable stash. Curing weed can take a long time (up to a good 2 years). It all depends on how much of a perfectionist you are. For good quality cannabis, our recommendation is to cure for around a month.

    Vacuum Curing Weed in Tightvac or Weck Preserving Jar

    You can only cure weed in an airtight space. Only then can you control the humidity. We recommend an airtight storage jar such as a Tightvac or Weck jar. These jars are hermetically sealed. That means they are airtight and odour-free. The nice thing about a glass Weck jar is that you can always view the contents. A Tightvac, on the other hand, is rather more discreet and thus more suitable if you want to store or conceal it.

    Curing weed in a number of steps

    1. Take an airtight storage jar such as a Tightvac or Weck jar and fill it ⅔ full with weed. The remaining space is needed to allow the air and bacteria to do their work. So don’t completely fill up your jar!
    2. Put the jar in a cool and dark place. The ideal temperature is the same as for drying weed: 18 to 21 degrees.
    3. Place a humidity regulator (e.g. Integra Boost sachets) in the jar. These sachets will ensure that the humidity remains optimal. You can read more information about the ideal humidity for curing and storing weed below.
    4. Open the jar on a daily basis and check for mould or other undesirable issues. Opening the jar also provides fresh air. Does the jar smell damp and musty? If so, the space is too moist. Adjust this and watch out for mould!
    5. Every so often, it’s a good idea to empty the weed out of the jar and put it back in. In this way, every part of the bud gets an equal chance at optimal ripening.
    6. From the fourth week onwards, we recommend you sniff it properly each day. Does the weed smell better than it did prior to curing? If so, then it’s working. But is it still not optimal? In that case, just continue the curing. Don’t forget to replace your humidity regulator if necessary.

    Humidity for Curing and Storing Weed

    The ideal humidity for curing and storing weed is between 55% and 62%. Humidity regulators which maintain this percentage can be obtained from us.

    • We recommend an air humidity of 62% for curing weed because this produces weed with the best smell and taste.
    • As far as storing weed is concerned, here personal taste has more of a role to play. Do you like dry weed that burns nice and easily and is also strong? In that case buy the 55% sachets. Or do you just want slightly heavier buds? Then it’s best to choose the 62% sachets.

    The humidity regulators from Integra consist of glycerol and water on a plant base. They self-regulate the humidity, inhibit mould or top rot and prevent loss of smell, taste and potency. On purchase, Integra sachets are supplied with indicator cards which show you when you need to replace them.

    Finished curing weed and curious about how many grammes you’ve cultivated? With one of our Precision Weighing Scales you’ll know exactly how big your harvest is!

    Storing Weed

    Once you’ve determined the correct humidity of your weed and the smell, taste and potency is optimal then you’re ready to store your weed. As you’ve read, it’s up to you to decide the ideal humidity for this. Anyway, there are a number of products in which you can store your weed. Examples are Tightvac storage containers, Weck jars, sealable bags or zipper bags.

    What can you do with your Weed Harvest?

    Curious about all the things you could do with your weed harvest? Short of inspiration or on the lookout for new ideas? We’ve written a blog on the things you can do with your harvest. Read the blog ‘8 things you can do with your Harvest‘ and be surprised!

    Is it time for you to dry and cure your weed? Does it need doing straight away? Read the rules for this here where you’ll also find a step-by-step plan for 3 different drying techniques!