Weed Grow Guide by Royal Queen Seeds

By Steven Voser


Key Points

  • Various species of mold grow on weed buds in humid conditions.
  • Moldy marijuana poses health hazards and must be discarded.
  • Learn how to identify moldy buds to ensure a safe smoke.
  • Learn how to prevent mold in the future to protect your flowering plants and stash of processed buds.

When growing marijuana, the work doesn’t stop at harvest time—you have to take steps to prevent mold from infecting your buds during drying, curing, and storage.

Fail to take these measures, and you risk mold spoiling your entire harvest. Not only does mold on weed degrade bud quality, but it makes marijuana dangerous to use.

Continue reading to find out how to safeguard your stash against these fungal foes, ensuring freshness, smoothness, and safety along the way.

A close-up of mold growing on a cannabis bud. The mold is a white, fuzzy substance that covers the surface of the bud.

What Makes Marijuana Buds Moldy?

Can weed get moldy? It certainly can. Marijuana flowers have the potential to become moldy during two distinct times: before harvest, when they’re still on the plant, and after harvest, during drying, curing, and storing.

During the flowering phase of the growing cycle, when buds are still attached to the branches of living plants, excess humidity and lack of airflow can cause mold to proliferate.

Marijuana buds also become moldy when they are incorrectly dried, cured, and stored. Errors during these steps fail to remove excess moisture from flowers, leaving them prone to mold that develops after the growing cycle has come to a close.

As a marijuana grower, you’ll drastically improve your knowledge and skill set by learning how to identify, prevent, and treat mold on your buds.

Types of Mold That Affect Marijuana

Several types of fungi have an appetite for marijuana buds. Check out the main culprits below and when they tend to strike:

  • Botrytis cinerea: This pathogen causes symptoms commonly known as “bud rot”. It affects buds during their development, arising in overly humid conditions and causing internal decay. 
  • Powdery mildew: This fungus develops on the leaves and buds of plants during growth, especially in conditions of high humidity and poor ventilation.
  • Rhizopus & Mucor: These molds also affect plants during growth and thrive in moist environments. They often strike after bouts of heavy rain.
  • Aspergillus: As one of the primary pathogens that infect flowers during storage, this mold frequently contaminates poorly dried and cured buds.
  • Penicillium: Another mold that commonly impacts buds during storage, Penicillium often infects buds when humidity is too high, or those not stored in airtight containers.
A collage of images showing different types of mold that can affect cannabis plants. The types of mold shown are Botrytis cinerea, powdery mildew, Rhizopus and Mucor, Aspergillus, and Penicillium.

How to Spot Mold on Weed

It’s important to keep an eye out for mold on weed during flowering and post-harvest. While disappointing, you must discard infected buds, as they pose a health hazard when smoked.

Check out the following sections to learn the different signs of mold and how to differentiate infected buds from healthy ones.

  • Signs of Mold: Fresh vs Dried Bud

The typical visual and physical signs of mold on marijuana include:

Powdery spots Weed flowers infected with powdery mildew exhibit white, gray, or light yellow powdery spots.
Fuzzy or web-like texture Both Botrytis and Aspergillus create fluffy or cobweb-like structures on or between buds.
Unusual colors Unusual shades of grayish-brown indicate Botrytis; hues of blue, green, and black are indicative of Penicillium and Aspergillus infections; yellow patches are the result of powdery mildew infections. 
Glossy or slimy appearance Some molds cause an unnaturally shiny or wet appearance on buds.
Brittle and crumbly Advanced mold infections can change the texture of buds, sometimes causing them to dry out and become brittle.
Slimy touch Molds can also cause infected buds to feel excessively moist and sticky, in a way different from the typical stickiness of resin.

  • The Difference Between Mold on Weed and Trichomes

Healthy cannabis buds have a frosty, sugary appearance, owing to the layer of trichomes on their surfaces. These glandular structures are responsible for manufacturing cannabinoids and terpenes and excreting them in the form of a viscous resin.

To the untrained eye, a thick coating of trichomes could easily be mistaken for mold. However, there are a few key giveaways that help growers tell the two apart.

First, pay attention to color. Trichomes vary from translucent to milky and amber, based on their maturity. You can use simple magnification tools, such as a handheld microscope, to get a closer look at them. In contrast, mold can exhibit all of the unusual colors listed above, including yellow and gray.

Second, take shape and texture into consideration. Trichomes are structurally distinct and have an upright, ordered, and almost “crisp” appearance. Conversely, mold either occurs as spots or a homogeneous web, often sprawling out chaotically.

  • The Importance of Smell Tests

Aside from its unique psychoactive effect, marijuana has gained recognition because of its standout aroma. Apart from color and texture, smell also helps to differentiate healthy buds from moldy ones.

The smell of healthy weed flowers varies because of the difference in aromatic molecules between strains. However, all healthy buds should smell pleasant, herbal, and somewhat skunky. You’ll detect fruity, earthy, floral, and gassy notes depending on the strain.

Moldy weed, in contrast, smells unpleasant. You’ll pick up on musty notes alongside hints of stale hay.

The Risks of Smoking Moldy Weed

You should never smoke moldy weed. As a health hazard, buds infected with mold pose the following dangers:

Respiratory issues Mold spores can cause coughing, wheezing, and chest pain.
 Allergic reaction Some people may experience allergic reactions following mold exposure, including sinus pain and upper respiratory inflammation.
Lung infections In severe cases, smoking moldy cannabis can trigger serious lung infections caused by mold spores.

How to Prevent Mold on Weed

Finding mold on the buds you worked hard to grow is nothing short of devastating. Therefore, all cannabis growers should educate themselves on how to keep weed from molding. Keep these tips in mind when raising your plants:

Monitor Place a hygrometer in your growing space to get real-time feedback on humidity and temperature.
Promote airflow Use inline and clip-on fans indoors and in greenhouses to prevent stagnant air.
Manage humidity Use a dehumidifier indoors when humidity climbs over 40% indoors during flowering. 
Shelter & shaking Protect outdoor plants from excess rainfall by erecting tarps or moving potted plants into greenhouses or polytunnels. Shake off excess moisture from the canopy.
Dry & cure properly Employ optimal drying and curing practices. Dry your plants until the stems break when bent. Burp your curing jars and use Moisture Fighters to keep humidity within an optimal range.

How to Test for Mold on Weed

You should consistently test your weed flowers for mold during bloom and after harvest. Use these techniques to ensure a safe smoke:

Visual inspection Look for unusual colors, textures, and spots, making sure to rule out trichomes. Use handheld magnification to get a closer look.
Touch test Your buds should feel sticky but not slimy or overly brittle.
Smell test Healthy buds should smell fresh, skunky, and floral, herbal, earthy, or sweet. Notes of mustiness and hay are signs of mold.
Use a blacklight Some molds glow under ultraviolet light, including Botrytis, Penicillium, and Aspergillus. Use a blacklight if you’re unsure.

Download our Pro Growing Guide for precision humidity and airflow protocols, advanced drying & curing schedules, and storage strategies that keep mold out of your grow.

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Keeping Mold 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 flavor, aroma, and potency, all the while keeping them safe from mold.

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 moldy weed is dangerous for your body!

Humidity Packs Protect Against Mold

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 mold.

  • 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 flavor.

  • 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.

Video id: 510269030

What to Do if You Find Moldy Buds

If you find moldy buds during flowering, immediately remove affected plants and discard them. Monitor your other plants closely both pre- and post-harvest, as early infections are very difficult to detect.

Post-harvest, discard all buds with any signs of mold. Do not try to salvage any jar that contains moldy buds, even if other buds seem unaffected.

Make an effort to sanitize your growing space, curing jars, and equipment. All of these are potential vectors of transmission.

Protect Your Weed From Mold

You now know what causes bud rot, you’ve learned how weed gets moldy, and you’re aware of how to keep fungal foes at bay. 

Use the information above to minimize the chances of mold wrecking your harvests. Dial in your temperature and humidity, and closely examine your flowers both before and after harvest.

If you ever encounter mold, don’t get discouraged! Discard your buds and start afresh. View it as a learning experience, and don’t risk your health trying to remediate contaminated buds.

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Privacy Policy - Royal Queen Seeds

To ensure a safe online environment and guarantee adequate data protection, we strictly comply with all legal requirements. In this privacy statement, we provide information about how and for what purpose data is collected, safety measures, storage periods and contact details.


COMPANY NAME: SNORKEL SPAIN, SL (hereinafter ROYAL QUEEN SEEDS)

C/ Vilar d'Abdelà, 5 (nave 1) CP: 08170 de Montornès del Vallès

+34 937 379 846

support@royalqueenseeds.com


The present Privacy Policy sets out the terms on which we will treat personal data at ROYAL QUEEN SEEDS; this includes any personal data collected through our website https://www.royalqueenseeds.com/ as well as any other data we process in the course of our business activities.

ROYAL QUEEN SEEDS collects the following personal data for the purposes listed below:

SECTION 1 – PERSONAL INFORMATION WE COLLECT

1.1 Account purchases

Account purchases can only be made if you are in possession of a personal account. When you create an account or purchase something from our shop, as part of the buying and selling process we collect the following personal information that you provide to us:

This information is required for delivery. In addition, when you browse our shop, we automatically receive the Internet Protocol (IP) address of your computer. Based on this information, we can optimise your online experience and at the same time protect our online environment.

Purpose of data collection

We collect and store account-related data for the following purposes:

(a) to carry out obligations arising from any contracts between you and us, and to provide you with information, products and services that you may request from us;

(b) to set up, manage and communicate with you about your account and your orders;

(c) to conduct market research and analysis;

(d) to confirm your age and identity, and to detect and prevent fraud.

1.2 Newsletters

With your explicit permission, we may send you newsletters about our shop, new products and other updates. We send newsletters based on your explicit consent. In the event that you purchase a product, and in accordance with current regulations, we may send you commercial communications in accordance with the legitimate interest of our company, always about products or services similar to those you have purchased or contracted. In any case, you may exercise your right of opposition through the channels announced in this Privacy Policy. The following information is collected in relation to the newsletter:

We do not need to know the sex of the person in order to send the newsletter (data minimisation: by law we must ask for data that is strictly necessary to provide the service, and in this case knowing the sex is not necessary to send the newsletter).

Purpose of data collection

The data collected is used to:

(a) personalise our emails, including your name and gender;

(b) provide gender-specific content.

You can withdraw your consent at any time by using the link provided in the newsletter or the contact information provided in section 2.

1.3 Customer service and contact form

In order to provide appropriate support, our customer service employees have access to information related to the account. Consequently, their support will be highly effective and friendly. The data provided in our contact form is used by our CRM provider, SuperOffice. We will only use your details to respond to your message.

SECTION 2 – LEGITIMATE INTEREST

If you have purchased any of our products, please note that we may process your personal data for promotional purposes, based on Royal Queen Seeds' legitimate interest only to offer you products or services from our company and about products or services similar to those you have purchased. You may exercise your right to opt out of future messages by the means set out in this Privacy Policy or through any notification you receive.

2.1 How do you withdraw consent?

If you change your mind, you can withdraw your consent for us to contact you for the purpose of collecting, using, or disclosing your data at any time by reaching out to us at: support@royalqueenseeds.com.

SECTION 3 – DISCLOSURE

We may disclose your personal information if we are required to do so by law or if you breach our Terms of Service.

SECTION 4 – HOW LONG DO WE KEEP YOUR DATA?

At Royal Queen Seeds, we will not retain your data for longer than is necessary for the purposes described in this Policy. Different retention periods apply for different types of data; however, the longest period we will normally hold any personal data is 10 years.

4.1 Account information

Data relating to the account remains relevant for as long as the consumer is in possession of an account. Therefore, the data remains documented for as long as the account exists. When our customers delete an account, the associated data will be deleted within a reasonable period of time. Requests regarding the inspection or correction of stored personal data or the deletion of an account can be sent to support@royalqueenseeds.com.

4.2 Newsletters

In the event that you give us your consent to inform you about our products or services, we will keep your data until you express your wish not to receive any further communications from us. However, we regularly (every month) carry out a relevance check. Registered customers (and their personal information) will be deleted whenever customers do not reply to our request. In addition, our newsletter mailing has an opt-out feature. Consumers can withdraw their consent by using this opt-out feature.

SECTION 5 – COOKIES

Cookies are small information files that notify your computer of previous interactions with our website. These cookies are stored on your hard drive, not on our website. Essentially, when you use our website, your computer displays its cookies to us, informing our site that you have visited before. This allows our website to function more quickly and remember aspects related to your previous visits (such as your username), making your experience more convenient. At Royal Queen Seeds, we use two types of cookies: functional and analytical.

5.1 Functional Cookies

Functional cookies are used to enhance your online experience. Among other things, these cookies track what is added to your shopping cart. The use of these cookies does not require prior authorization.

5.2 Analytical Cookies

Analytical cookies are used for research and market analysis. The data collected with these analytical cookies is anonymous, making it unusable for third parties. The use of these cookies does not require prior authorization.

SECTION 5 – THIRD-PARTY SERVICES

Third-party services are required to conduct transactions and provide our services. In general, the third-party providers we use will only collect, use and disclose your information to the extent necessary to enable them to perform the services they provide to us.

However, certain third-party service providers, such as payment gateways and other payment transaction processors, have their own privacy policies regarding the information we must provide to them for your transactions.

We encourage you to read the privacy policies of these providers so that you can understand how these providers will handle your personal information.

In particular, certain suppliers may be located or have facilities located in a different jurisdiction than yours or ours. Therefore, if you choose to proceed with a transaction involving the services of a third party, your information may be subject to the laws of the jurisdiction in which that service provider or its facilities are located.

Once you leave our website or are redirected to a third-party website or application, you are no longer governed by this Privacy Policy or the Terms of Service of our website.

Web analytics service (anonymous data)

On this website we have integrated an element of a web analytics service (with anonymisation functionality). Web analytics can be defined as the gathering, processing and analysis of data about the behaviour of visitors to websites. An analytics service collects, among other things, data about which website a person came from (the so-called referrer), which sub-pages they visited or how often and for how long they visited a sub-page. Web analytics is mainly used for website optimisation and for a cost–benefit analysis of internet advertising.

Courier service

To complete deliveries we use a courier service. This courier service carries out the delivery between our company and the consumer's home. To complete these logistics, the company requires access to the consumer's name and address information.

Mailing service

Royal Queen Seeds uses a third-party mail service provider to send its newsletter. This provider has access to limited account information related to opt-in consent (e.g. email address).

Marketing services

Royal Queen Seeds has the support of a company that specialises in marketing and communication activities. Their access to personal information is very limited and mostly anonymous.

Payment services

At Royal Queen Seeds we use external payment services to handle our transactions (e.g. credit card payments).

SECTION 6 – SECURITY

To protect your personal information, we take reasonable precautions and follow industry standard best practices to ensure that it is not inappropriately lost, misused, accessed, disclosed, altered or destroyed.

If you provide us with your credit card information, the information is encrypted using secure socket layer technology (SSL) and stored using AES-256 encryption. Although no method of transmission over the internet or electronic storage is 100% secure, we follow all PCI-DSS requirements and implement additional industry standards that are commonly accepted. Information related to the account is protected with a hashing method. This method transforms the information into a generated hash. As a result, confidential information is protected and invisible, even to us. In addition, our databases are exceptionally protected against unauthorised access. For example, access to the database is only possible and permitted via approved IP addresses (e.g. from Royal Queen Seeds headquarters). Other attempts and addresses are rejected at all times.

Furthermore, data is anonymised as much as possible, so it cannot be directly linked to a specific consumer. With this data, however, we may be able to carry out market research and analysis. In addition, the third parties concerned (e.g. mailing service) are examined prior to our collaboration, comply with the GDPR from the EU and receive a processing agreement. Within Royal Queen Seeds, employees are assigned different access permissions. Specific permission provides access only to information that is strictly required to perform a task. Digital security measures are subject to change and must meet high requirements to ensure the safety of online customers. That is why, at Royal Queen Seeds, we appoint a security officer. Regular verification and improvement of security measures (where necessary) are part of the role.

SECTION 7 – CHANGES TO THIS PRIVACY POLICY

We reserve the right to modify this Privacy Policy at any time, so please check back regularly. Changes and clarifications will be effective immediately upon being published on the Website. If we make substantial changes to this policy, we will notify you here that it has been updated so you will know what information we collect, how we use it and under what circumstances, if any, we use and/or disclose it.

SECTION 8 – YOU HAVE THE RIGHT TO: