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Bud rot solutions: Identify, treat, and prevent it fast
Bud rot is the silent killer of cannabis crops
Capable of destroying your entire harvest before you even realise it’s there.
If you ignore it, bud rot will spread like wildfire, turning your prized buds into unusable mush.
But don’t worry; this guide will show you how to identify, treat, and prevent cannabis bud rot fast, saving your plants and your hard work.
In this post, you’ll learn what causes bud rot, how to spot it early, and the steps you need to take to stop it in its tracks.
Disclaimer: Any information given on this site is for educational purposes only. Please ensure if you’re growing cannabis, you’re doing so by the law and subject to appropriate permissions and licenses of the applicable country.
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What is bud rot?
Bud rot, also known as Botrytis cinerea, is a type of mould that attacks cannabis buds, turning your hard work into a grower’s nightmare.
It thrives in moist, humid conditions, often caused by high relative humidity and stagnant air, and spreads rapidly if left unchecked.
You’ll usually encounter it during the flowering stage, but it can also strike during the drying process if environmental conditions aren't properly managed.
What does bud rot look like?
Initially, you might notice fluffy white mould, but this can quickly transform into grey mould or brown patches, causing the infected area to die.
When bud rot progresses, it starts at the centre of the bud, where excess moisture gets trapped.
Worse still, botrytis spores can spread to nearby cannabis buds and infected plants, potentially wiping out your entire crop.
While outdoor plants often face bud rot due to morning dew and rain, indoor growers aren’t immune.
Without adequate air circulation or humidity control in the grow room, conditions can favour mould growth.
Prevention is crucial, and understanding what causes bud rot is your first step toward protecting your precious cannabis plants.
What causes bud rot?
Bud rot develops when moisture and poor air circulation create the perfect environmental conditions for mould spores to germinate.
Here’s a breakdown of the leading causes:
High humidity: When relative humidity levels rise, especially during the late flowering stage, condensation forms inside the buds.
This traps moisture, creating a breeding ground for mould spores to spread.
Poor air circulation: Still air around dense plants allows moisture to settle on buds.
Without consistent airflow, areas deep within the plant material become vulnerable to rot.
Warm temperatures: Combine heat with high humidity, and you’ve created an ideal environment for mould growth.
Dew point issues: Outdoor growers frequently deal with dew, which wets buds and starts the rot cycle.
Overcrowded plants: Tightly packed plants, particularly those with larger buds, block airflow.
Surplus plant material like excess fan leaves contributes to this problem.
Standing water: In both indoor and outdoor settings, pooled water encourages rot.
Signs of bud rot
Spotting bud rot early is crucial if you want to save your plants.
Look out for these tell-tale bud rot symptoms:
White fluffy mould: The early stages of bud rot often show as small patches of white, fluffy mould on the buds, which can spread rapidly if ignored.
Brown or grey patches: As bud rot progresses, you may notice brown bud rot or grey mould forming, discolouring the affected areas.
These patches often feel mushy and are a clear indicator of infection.
Buds turning purple or brown: Infected buds may change colour, a sign that the plant material is dying.
Unusual odour: Another red flag is a musty, damp smell in your grow room or around your plants.
Spreading mould: If left unchecked, the mould will move beyond the buds, threatening the entire plant.
Inspect your plants daily, especially during the flowering stage.
Early detection not only helps you catch bud rot but also allows you to take swift action to prevent it from ruining your whole crop.
Act quickly to remove infected plants and manage humidity levels effectively.
Bud rot treatment:
If you’ve spotted signs of bud rot, it’s time to act fast. Here’s what you need to do:
1. Remove infected buds immediately
Carefully cut away all infected buds and dispose of them far from your grow space.
Don’t try to salvage mouldy cannabis - it’s unsafe to consume (particularly for those with a compromised immune system) and produces spores that can infect other plants.
2. Sterilise your tools
After removing infected plant material, sterilise your scissors or trimmers with alcohol or bleach.
This step prevents spores from spreading to healthy plants.
3. Increase air circulation
Place oscillating fans strategically to improve airflow around your plants and all the buds.
Focus on areas prone to still or stale air, especially near the base of dense plants or around denser buds.
4. Control humidity
Lower the relative humidity in your grow room to ideally below 60% if not lower.
For outdoor growers, prune unnecessary plant material to promote better airflow.
5. Monitor daily
Check your cannabis plants daily for new signs of bud rot.
Acting decisively can stop bud rot from spreading and save what remains of your valuable cannabis buds.
How to prevent bud rot
Prevention is always better than treatment. Here’s how to avoid bud rot:
Control humidity
Invest in a Grow Sensor or hygrometer to monitor the relative humidity in your grow room. During the flowering stage, keep it between 40% and 60%.
If you grow outdoors, consider planting in areas with good airflow to naturally lower humidity. Some growers also use a leaf blower to remove dew from plants.
Improve airflow
Use oscillating fans and an exhaust fan to eliminate stagnant air.
This ensures your plants are surrounded by fresh, moving air, which is vital for preventing fungus spores from settling.
Prune dense foliage
Removing excess plant material, especially from leafy plants, allows air to reach even the thickest buds.
This reduces the risk of moisture build-up in hidden spots.
Choose resistant strains
Opt for strains bred for bud rot prevention if you're in a humid climate.
These strains are better equipped to thrive in challenging environments.
Avoid overwatering
Water only when necessary to minimise moisture in the soil and around the base of your plants.
Use preventive measures
Products like natural anti-fungal sprays can reduce the chance of mould taking hold, especially on cannabis plants grown outdoors.
Creating an optimal growing environment with proper airflow and appropriate humidity ensures your cannabis buds stay healthy and mould-free.
Using a Grow Sensor to prevent bud rot
The Grow Sensor is one of the smartest investments you can make to protect your plants and prevent bud rot.
It monitors key environmental factors like humidity, temperature, VPD and dew point in real-time, ensuring you maintain a stable and healthy growing environment.
Get proactive alerts: The Grow Sensor warns you of high relative humidity, VPD or dew point issues before conditions allow botrytis spores to thrive.
Real-time tracking: The easy-to-use app monitors and reports fluctuations in temperature and humidity 24/7, helping you address potential risks as soon as they occur.
Automation: The Grow Sensor automates environmental checks, eliminating the need for daily manual monitoring and saving you time and effort.
By detecting early warning signs, a grow sensor enables you to act fast, minimising the chance of losing your entire crop.
Serious about achieving consistent results? This tool is a must-have for growers who want to stay one step ahead of bud rot prevention.
Preventing post-harvest bud rot
Bud rot doesn’t stop once you’ve harvested your plants.
Spores can still ruin your hard-earned buds if the drying process isn’t managed carefully.
Drying space conditions
Keep humidity below 60% and ensure proper airflow using fans. This helps prevent mould spores from taking hold during this critical stage.
Avoid overcrowding
Hang branches with enough space between them to allow even airflow. Crowding can trap excess moisture, leading to mould growth.
Inspect buds regularly
Check daily for signs of bud rot or grey fuzzy mould on your drying buds. Acting early can save your entire crop.
Use hygrometers and sensors
Monitor relative humidity and temperature closely to avoid conditions that allow spores to germinate.
A grow room with controlled settings ensures a safer post-harvest environment. You can use the Grow Sensor for that, too!
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Common mistakes to avoid
Even experienced growers can make mistakes that lead to bud rot. Here’s what to avoid:
Overcrowding plants
Tightly packed plants, especially leafy plants, restrict the circulation of air and trap excess moisture. Ensure there’s adequate spacing to allow airflow around your cannabis plants.
Ignoring maintenance
Neglecting your HVAC system can lead to still air, increasing the risk of fungus spores spreading. Regular maintenance is essential.
Skipping inspections
Failing to inspect plants daily during the flowering stage means you might miss the early stages of infection. Check for gray fuzzy mould or damp spots regularly.
Overwatering
Too much water creates a breeding ground for spores. Allow soil to dry out between watering sessions.
Underusing tools
Overlooking tools like grow room monitors means missing critical environmental control. These devices are invaluable for monitoring and optimising your grow room.
Takeaways
Bud rot is undeniably the arch-nemesis of cannabis growers, capable of destroying an entire harvest if left unchecked.
However, with the right knowledge and strategies, you can keep it at bay.
Understanding what causes bud rot, whether it’s excess moisture or poor airflow, is your first line of defence.
Recognising early signs like white mould or discoloured buds ensures you can act quickly to minimise damage.
Investing in tools like the Grow Sensor to track humidity and other environmental metrics and maintaining proper airflow in your grow room are essential steps in protecting your plants.
Prevention is always better than cure, and being proactive with daily inspections, pruning, and monitoring is key to staying ahead of this issue.
With vigilance and care, you can ensure your cannabis plants remain healthy, and your buds reach their full potential.
Happy growing!
FAQs
Can bud rot buds be saved?
Unfortunately, once bud rot has infected buds, they can rarely be saved.
Infected buds should be removed immediately to prevent mold growth from spreading to the rest of the plant.
Attempting to salvage bud rot buds is risky, as consuming moldy cannabis can be harmful.
Instead, focus on removing all affected areas of bud mold and sterilising your tools.
To avoid losing your entire crop, inspect your plants daily, especially during the flowering stage.
Preventive measures, such as maintaining proper airflow and humidity, are the best way to prevent bud rot from spreading further.
How do you cure bud rot?
There is no way to "cure" bud rot on weed, but you can manage it by cutting out the infected buds as soon as you notice symptoms.
Remove dense plants or unnecessary plant material to improve airflow and reduce the risk of mold spores spreading.
Lower the relative humidity in your grow room or outdoor area and increase air circulation using fans.
Ensure all infected plants are disposed of properly to avoid reinfection.
Remember, prevention is key - monitor your growing environment closely to stop bud rot before it progresses.
What is the main cause of bud rot?
The main cause of bud rot is excessive moisture combined with poor airflow.
High humidity levels in the grow room or outdoors create the perfect environment for mold spores to germinate.
Factors like standing water, poor airflow, and warm conditions contribute to its development.
Managing the growing environment, including temperature and humidity, is essential to preventing mold issues.
Can bud rot affect other plants?
Yes, bud rot can spread to other plants if left unchecked.
The mould produces airborne spores that can travel and infect neighbouring crops, particularly in environments with stagnant air or high humidity.
Even outdoor growers aren’t safe, as wind can carry botrytis spores across large distances.
Remove infected plants quickly to minimise risk and ensure proper airflow and humidity in your grow space.
Regularly inspect the health of all plants to catch potential issues early.
Does bud rot affect potency?
Yes, bud rot drastically reduces the potency of infected buds.
As the mould progresses, it breaks down the cannabinoids and terpenes within the buds, making them less effective and desirable.
Worse still, mouldy cannabis can be unsafe to consume due to the presence of harmful spores.
To preserve the potency of your crop, act quickly when you notice signs of bud rot.
Removing affected areas of weed bud rot and maintaining a healthy growing environment with the right humidity levels and airflow are essential.
Should I harvest plants early if I have bud rot?
Harvesting early can sometimes be a smart move if bud rot is present, but it depends on the severity and spread of the infection.
If the bud rot attacks are isolated to a few infected buds, you can remove affected buds immediately and closely monitor the remaining plant.
However, if bud rot progresses or conditions like high humidity levels and poor airflow persist, you may need to harvest immediately to save your crop from total loss.
If you harvest early, ensure a proper drying process with controlled humidity to prevent post-harvest mould issues.
While early harvesting may reduce potency, it’s often better than losing your whole crop.
Cannabis bud rot vs mould - what’s the difference?
Bud rot is a specific type of mold caused by Botrytis cinerea, a fungus that thrives in humid, poorly ventilated environments.
It targets buds, starting deep within their dense structure and spreading quickly if unnoticed.
Bud rot progresses through stages, from fluffy white mould to gray mold or brown decay, ultimately destroying the bud.
Mould, on the other hand, is a broader term referring to various fungi that can grow on plants, including cannabis buds.
While bud rot is one type of mould, others, like powdery mildew, affect other parts of the plant, like leaves or stems.
Proper airflow and humidity levels help combat both.
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