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Avoid mold when drying cannabis

In this article we will tell you about the cannabis processing phase: drying. How to avoid mold in our cannabis inflorescences? How should we proceed to carry out correct processing? Read the whole article to discover the secrets of a very important phase, which avoids annoyances and problems resulting from mold and other bacteria. Specifically we will talk to you about:

  1. The importance of drying
  2. Drying
  3. What are the most dangerous molds
  4. When is there a risk of mold developing?
  5. Some remedies

Cannabis light

The importance of drying

You have carefully and apprehensively followed all the development and growth phases of your plants, which are now ready to be harvested. You will probably think that - at this point - most is done, and it is partly true, but the drying phase is very important . This process should not be underestimated, because getting something wrong at this stage could nullify the efforts of the previous months. The drying phase is also very important for the flavor and effect that your cannabis will have once ready to be consumed.

When the buds are ready, you have to put aside your impatience and wait for the right time to taste the fruit of all your efforts. You need to be careful, especially to prevent your precious buds from being attacked by mold. Fresh marijuana buds contain a lot of water and doing something wrong in the drying process, or accelerating it, could lead to the formation of dangerous molds, especially Botrytis and powdery mildew.


Drying is an essential step in removing moisture from buds. The most used method for drying freshly harvested marijuana is to hang the buds upside down , so that they can dry slowly and naturally , without the aid of artificial devices, which speed up the process, but can become potentially harmful to the cannabinoids and the other active compounds contained in the plant.

The techniques for hanging and drying plants depend above all on the resources and space available to the grower. The drying area must be large and free of light, with a constant temperature of around 20-21° and a humidity of around 50% . To hang the buds, you can use commonly used and easily available materials, such as wires, ropes or strings , as long as they are sturdy enough to support the weight of the plant.

A completely darkened room must be kept properly ventilated to create adequate air circulation which will prevent the formation of mold or fungi.

To avoid the formation of mold and fungi, it is very important that temperature and humidity remain constant: the temperature can be controlled using heaters and air conditioners , while the humidity can be measured with a hygrometer and regulated using humidifiers and dehumidifiers , depending on the conditions of the room. chosen environment. The drying process takes a total of 9 days, during which it is essential to carefully check that there are no signs of mould.

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What are the most dangerous molds?

  • Botrytis cinerea is a fungus of the Sclerotiniaceae family, and attacks many varieties of plants, including cannabis and vines. The Latin name “cinerea” refers to the ash gray color taken on in particular by grapes when attacked by this species.

When Botrytis attacks the marijuana plant it tends to initially attack the base of the plant's stems , making its identification rather complicated. Usually the first visible signs can be seen on the smaller leaves , especially those arranged around the buds , which tend to wither, discolor and dehydrate. You can also notice a whitish fuzz inside the buds and on the stems of the leaves near the flowers.

It usually takes on greyish, blue-greenish or white colors . When the humidity is too low, Botrytis could cause dehydration of part or all of the bud, which will tend to crumble to the touch; when the humidity is high it can instead envelop the flowers, leading them to decompose and take on a mushy consistency.

If identified at this stage it will still be possible to stop the advance of this fungus. However, if you notice the problem after a long time, you will probably find Botrytis in an already advanced stage, characterized by small circular black formations distributed on the surface of the mould. Well yes, they are mold spores, ready to spread throughout your grow with a light mass of air.

  • Powdery mildew , also called white mite, fog or albugo, is a trophic plant disease caused by Ascomycota fungi in the asexual phase of the cycle, previously identified with the genus of imperfect fungi Oidium.

It appears as a thin layer of powdery, whitish mold present on the surface of the leaves of Cannabis plants, which are attacked first, before the "white disease" spreads to the entire plant. Powdery mildew inhibits photosynthesis , blocking the cannabis plant's energy sources and, consequently, leading to its death. The leaves curl up, turn yellow, turn brown and finally die .

Although it is difficult to detect in its early stages of development, powdery mildew tends to appear on diseased leaves in the form of small, raised circular spots. Like Botrytis, powdery mildew also develops small black spores, visible in its most advanced stage, which spread easily even in indoor crops.

Both of these types of mold can develop both indoors and outdoors and can infect a large number of Cannabis plants in a short time; this is why they are extremely dangerous even on a single specimen, it is easy for them to spread quickly throughout the entire plantation.

Fortunately, these molds tend to appear and develop only in certain circumstances, which must be followed by some specific conditions before they can spread to an entire plant.

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When is there a risk of mold developing?

Before Botrytis or powdery mildew can attack a plant, three specific conditions must exist: low temperatures, stagnant air and excessive humidity/water. The best way to prevent the attack of these molds is therefore to ensure that none of these parameters occur within a plantation and, at least, it is necessary to avoid them coexisting in the same phase.

The risk is lower for indoor cultivations, where it is easier to keep environmental parameters under control. It is very important to have a good ventilation system , to prevent the air from stagnating; it is then necessary to avoid the plants being too close together , a factor that could hinder correct air circulation. Thanks to a good ventilation system, the internal humidity of a grow room can also be kept under control.

In an outdoor grow, however, things can be a little more complicated. A poorly ventilated area, characterized by cool nights and frequent rain, could recreate the ideal conditions for mold growth. It is therefore essential to carefully choose the area intended for cultivation .

The threat of mold is always lurking, but increases as we approach the maturation of the flowers , which progressively swell, hindering intra-floral ventilation. Often large buds expose the plant to greater risks related to mold; many growers prefer to act with the so-called "apex pruning" in order to reduce the size of the upper buds. You will get smaller flowers, it's true, but they will be more numerous and above all healthier and safer. The small size of the buds reduces the amount of humidity and consequently the risk of falling victim to mold.

Drying cannabis

Another factor that must be paid attention to in order to avoid bud rot is irrigation , particularly during the last phase of flowering, when the harvest is imminent . Without neglecting temperature or humidity , in this phase it will be necessary to be careful about the quantity of water administered to the plants. You should never water plants unless you are sure they are short of water.

The third aspect to take into consideration is the size of the plants ; the thickest specimens are the most attractive to mold, and their size must be kept under control through pruning . This phase is the most delicate, because the closer to harvest the more the possibility of using chemical remedies, which could harm the consumer, is reduced.

Precisely for this reason, it is essential to strengthen preventive measures against mold : if any part of the plant were to be damaged, in most cases the solution will be to eliminate the entire specimen in order to avoid contagion. For mild infections, removing the affected areas may perhaps be sufficient, which would allow the remaining buds to be harvested unscathed. Let's not forget, however, that prevention is always better than cure.

Some remedies

The best remedy remains prevention. There is no better cure than preventing the problem! However, if you have not taken all the appropriate steps previously, there are other remedies that can help you.

To combat Botrytis the best option is to use organic sprays, such as products based on Bacillus subtilis (Serenade) , which can help treat Botrytis and keep it under control until harvest, but will never be able to eliminate it completely. To prevent the spread of mold, you can move infected plants to a warm room with extremely low humidity.

Against powdery mildew, however, some additional strategies can be adopted. There are some natural remedies that seem to work: you can add two teaspoons of apple cider vinegar in 1L of water and spray the solution on your plants, or you can prepare a mixture with 60% milk and 40% water and always spray it on plants. Both of these formulas have the ability to kill powdery mildew.

Beyond natural remedies, the first thing to do is to eliminate all diseased leaves and move the plant to a warm area with low humidity ; then you can proceed to apply a safe and specific fungicide spray to treat mold infections. This should go some way to keeping the spread of powdery mildew under control .

However, it is important to keep in mind that any fungicide-based treatment will irremediably compromise the final quality of the buds. These products, in fact, tend to alter the flavours, aromas and quality of the flowers themselves.

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