The cannabis industry is rapidly evolving, with stringent regulations in place to ensure product safety and quality. A consistently critical aspect of quality control is microbial testing, which assesses the presence of harmful microorganisms in cannabis products. The unfortunate truth is that many samples will fail for microbial testing, which is one of the toughest tests to remediate after failure. To avoid the potential pitfalls of microbial testing failures, cannabis growers must implement a series of best practices and preventive measures. Encore Labs wants to explore these recommendations to help cultivators navigate the challenges of microbial testing successfully and avoid microbial failings. 

Understanding Cannabis Microbial Testing 

Before delving into specific strategies, it’s essential to understand what microbial testing entails. This testing examines the presence of pathogenic bacteria and mold in cannabis products that can be lethal in high doses. The goal is to ensure that the final product is safe for consumption and free from contaminants. California state regulations mandate that there is a 48-hour waiting period to conduct a full microbial test, meaning that the test has to be conducted over the course of 2 days to allow for the growth of harmful microbials. If the sample shows no signs of these harmful microbials, then the sample passes and is safe to sell to the public. At Encore Labs, microbial failures occur about 1% of the time, and is a very common problem to experience within the industry.

Growing Conditions 

Begin your journey with quality genetics. Different cannabis strains exhibit varying susceptibility to microbial issues. Selecting strains with natural resistance can be a proactive approach to microbial management. Control environmental factors like temperature and humidity to create conditions less conducive to microbial growth. Proper ventilation and air circulation also help prevent stagnant air that can foster contamination. Overcrowded grow spaces can lead to poor air circulation and increased humidity, creating ideal conditions for mold and mildew. Proper plant spacing is essential for a healthy crop. It is also recommended to isolate new plants or clones for a period to ensure they are not introducing pests or pathogens into your main crop.  

Proper Hygiene and Sanitation 

Maintaining a clean and hygienic cultivation environment is paramount. Implement rigorous cleaning practices, dispose of waste properly, and ensure that employees follow strict hygiene protocols. Contaminants can originate from employees, equipment, or the environment, so cleanliness is key. Regularly clean and sanitize your equipment to prevent cross-contamination. Make sanitation a routine part of your cultivation process. Handle and store harvested cannabis correctly to avoid contamination. Use airtight containers and maintain appropriate humidity levels to preserve product quality.

Key Facility Operations 

High-quality irrigation water is essential. Invest in a reliable water filtration system to remove contaminants. Regularly monitor the water source to ensure it meets quality standards. Pests can introduce contaminants to your cannabis crop. Implement an effective pest management strategy to prevent infestations and reduce the risk of contamination. Regularly inspect your plants for signs of disease or microbial growth. Early detection can prevent more significant issues and enable swift corrective action. Ensure that your staff is well-trained in cannabis cultivation best practices, hygiene, and safety. Proper education is critical to maintaining a clean and safe environment. Maintain meticulous records of cultivation and sanitation activities. This documentation helps trace issues back to their source and demonstrate compliance with regulations when needed. 

Testing and Monitoring 

Frequent testing for microbials, including mold, mildew, and bacteria, is essential. Early detection is key to addressing issues promptly, preventing them from escalating. Use an accredited and compliant testing lab recognized by your state’s regulatory authority, such as Encore Labs. Reliable lab results are crucial for ensuring the safety of your products. 


If you experience microbial testing failures, know that you are not alone in this predicament. Work with your lab and use any feedback to identify the source of the problem and take corrective actions. Failure is an opportunity to learn and improve. Microbial testing in cannabis cultivation is a vital aspect of ensuring product safety and quality. By following these recommendations and staying informed about local regulations, you can minimize the risk of failing microbial testing and build a reputation for producing safe, high-quality cannabis products. Cultivating success in the cannabis industry begins with a commitment to best practices and a dedication to ensuring the well-being of consumers. If you need microbial testing or want to get started with some R&D testing for your grows, you can start testing with us here