Cannabis Bud Rot: 5 Possible Causes, Fixes & Prevention

Cannabis bud rot is one of the most common problems for beginning growers.

It’s also one of the most frustrating.

Once your buds have begun rotting, there is nothing you can do.

The buds are lost.

You may be able to save the plant by removing only the affected buds, but this rarely works out well.

Nevertheless, there are steps you can take to try to save at least some of your harvest.

More importantly, there are steps you should take to prevent bud rot from ever recurring again in the future.

We will cover both below: prevention, as well as what to do if you already have rotting buds. We’ll also cover the main causes of bud rot, since that information is invaluable for prevention.

 

Possible Causes Of Marijuana Bud Rot

The following are the most common causes of bud rot. If you notice your buds are starting to rot, it is almost certainly due to one of the following problems.

 

High Humidity

Perhaps you’ve heard the saying “happy mold loves a wet environment.” Well, that holds true for bud rot as well. Excessive moisture in the air creates a breeding ground for those pesky fungal spores.

Aim for a relative humidity level between 40 and 50 percent during the flowering stage. This helps prevent moisture from collecting on your buds, which can trigger bud rot development.

 

Poor Air Circulation

Imagine a stagnant pond compared to a flowing stream. Stagnant air acts like the pond, allowing mold spores to linger around your plants.

Good air circulation is crucial for removing excess moisture and preventing the buildup of spores. Without proper airflow, even with moderate humidity, spores can settle on your plants and germinate, leading to bud rot.

 

Plant Density And Canopy Management

When your cannabis plants are crammed together like sardines in a can, airflow suffers and humidity rises. This overcrowding creates the perfect environment for bud rot.

Proper spacing between plants allows for air to circulate freely and prevents dense foliage from trapping moisture. Regularly trimming some of the larger fan leaves also improves airflow within the plant’s canopy, further reducing the risk of bud rot.

 

Watering Practices

Overwatering your plants is another way to invite bud rot. When the soil is constantly saturated, it creates a humid microclimate around the base of the plant, which can eventually rise and affect the buds.

Water your plants only when the top inch of soil feels dry, and adjust watering frequency based on factors like pot size, plant size, and climate.

 

Temperature Control

While humidity plays a major role, temperature also influences bud rot development. Mold thrives in mild temperatures, typically between 68° and 77° F (20° and 25° C). Maintaining a slightly cooler temperature range during flowering can help slow the growth of mold spores.

However, be mindful of temperature fluctuations, because drastic changes in temperature can also stress your plants and weaken their immune system, making them more susceptible to bud rot and other issues.

 

Potential Fixes For Bud Rot

Unfortunately, there is no true “fix” for buds already infected with bud rot. Fungal spores spread quickly, and removing just the affected areas might leave behind microscopic spores that will continue to grow and spread the rot.

However, there are a few steps you can take to try and stop the rot from spreading:

 

Immediate Actions

• Isolate and Remove Infected Material: Act swiftly! The first line of defense is to identify and remove any buds or entire plants that show signs of bud rot. Carefully bag the infected material to prevent spores from escaping and dispose of it properly (not in your compost pile!).
• Sanitize Your Tools and Growing Area: Fungal spores can linger on tools and equipment. After removing infected material, thoroughly clean your tools (including scissors and pruners) with a disinfectant like a 10% bleach solution. Also, sanitize your grow area with the same solution to minimize the risk of remaining spores infecting healthy plants.

 

Environmental Adjustments

As discussed earlier, high humidity is a major culprit in bud rot development. Here’s how to tackle it:

• Dehumidifiers and Fans: Invest in a dehumidifier to remove excess moisture from the air. Pair it with fans to circulate the drier air throughout your grow space.
• Increase Ventilation: If possible, improve ventilation in your grow room by opening vents or installing an exhaust system. Fresh air exchange helps reduce overall humidity levels.
• Pruning and Training: Prune away excess foliage, particularly large fan leaves that might block airflow within the plant’s canopy. Consider techniques like “lollipopping” to remove lower branches and promote better air circulation around the bud sites.
• Oscillating Fans: Strategically placed oscillating fans will create a constant breeze that discourages moisture buildup and helps prevent spores from settling on your plants.

 

Watering Adjustments

• Watering Schedule: Re-evaluate your watering practices. Overwatering is a common contributor to high humidity. Adjust your watering schedule to allow the top inch or so of soil to dry out completely between waterings.
• Drainage: Ensure your pots have adequate drainage holes to prevent water from pooling around the roots and creating a damp environment.
• Watering Technique: Water directly at the base of the plant, avoiding wetting the leaves and buds. Wet foliage and buds can create an ideal breeding ground for mold spores.

 

How To Prevent Bud Rot From Occurring In The First Place

The best defense against bud rot is a good offense. Prevention is the best cure. Proactive measures throughout the growing cycle can significantly reduce the risk of infection. Here’s how to best prevent bud rot before it takes hold:

 

Environmental Control

• Maintain Optimal Humidity and Temperature: As discussed earlier, humidity and temperature play a crucial role in bud rot development. Aim for a relative humidity level between 40% and 50% during the flowering stage and keep the temperature range slightly cooler, ideally between 60° and 68° F (15° and 20° C).
• Monitor Conditions: Invest in hygrometers and thermometers to keep a close eye on humidity and temperature levels in your grow space. This removes the guesswork and allows you to make adjustments as needed to maintain optimal growing conditions.
• Climate Control Systems: Consider using dehumidifiers, exhaust fans, and air conditioners to create a stable environment with the desired humidity and temperature levels.

 

Proper Plant Care And Maintenance

• Regular Pruning and Defoliation: Regularly prune away excess foliage, especially large fan leaves that can block airflow and trap moisture within the plant’s canopy. Techniques like lollipopping can also be beneficial to prevent issues, since it involves removing lower branches to promote better air circulation around the bud sites.
• Training Techniques for Airflow: Use plant training techniques like SCROG (Screen of Green) or LST (Low Stress Training) to create an open canopy structure that allows for better air circulation throughout the plant.
• Spacing Between Plants: Don’t crowd your plants! Ensure there’s adequate spacing between them to allow for proper air circulation and prevent humidity buildup.

 

Water Management

• Avoid Overwatering: Overwatering is a recipe for disaster when it comes to bud (and root) rot. Water your plants only when needed; think Goldilocks!
• Watering Schedule: Adjust your watering schedule based on factors like pot size, plant size, and climate.
• Watering Technique: Water directly at the base of the plant, avoiding wetting the leaves and buds. This helps prevent moisture buildup on the foliage, which can encourage mold spores.
• Well-Draining Soil: Use a well-draining potting mix or growing medium to ensure excess water doesn’t pool around the roots, creating a damp environment.

 

Monitoring And Early Detection

• Inspect Regularly: Be vigilant! Regularly inspect your plants throughout the growing cycle, paying close attention to the buds, leaves, and stems for any signs of bud rot.
• Magnifying Tools: Use a magnifying glass to get a closer look at the developing buds. Early detection is key to preventing the spread of infection.

 

Choosing Resistant Strains

And finally, you can try choosing cannabis strains known for their resistance to mold and bud rot. Different strains have varying levels of susceptibility. Research reputable seed banks and inquire about strains with good mold resistance.

 

Cannabis Bud Rot: Final Thoughts

Bud rot can be a devastating problem for cannabis growers. But understanding the causes and taking proactive measures can significantly reduce the risk of infection.

High humidity, poor air circulation, overcrowded plants, improper watering practices, and fluctuating temperatures are the primary culprits behind bud rot development.

To prevent bud rot, maintain optimal humidity levels between 40% and 50% during the flowering stage, ensure good air circulation, and manage plant density and canopy effectively.

Avoid overwatering and ensure proper drainage, while keeping temperatures slightly cooler to inhibit mold growth. Regular pruning and defoliation, along with proper plant spacing, can further help in preventing moisture buildup.

If bud rot does occur, immediate action is crucial. Isolate and remove infected material, sanitize tools and the growing area, and make necessary environmental adjustments such as using dehumidifiers and fans to reduce humidity.

By following the guidelines in this article, you can create a healthier growing environment and protect your cannabis plants from the detrimental effects of bud rot, ensuring a successful and bountiful harvest.