Outdoor vs. Indoor Grows: How the Growing Environment Affects the Chemical Makeup of Cannabis

There are many differences to growing indoor vs. outdoor, but how do those differences affect the plant itself? We at MCR conducted an experiment to find out. Here’s what we found.

Every good experiment starts with a theory. Ours was that clones sharing the same genetic information would express different secondary metabolites (such as cannabinoids and terpenes) depending on the environmental conditions they are grown in. 

The experiment was set up using clones from five cultivars, which were split between both indoor and outdoor grows. These plants were grown through vegetative and flowering grow cycles, and then dried & cured before being sent to the lab for analysis. 

Two labs were used to test the samples, and each had a different approach to the analysis. At MCR Labs, we used a targeted quantitative analysis to test for cannabinoids, terpenes, and heavy metals. Our partners at SCIEX used an untargeted qualitative approach.

The Results

Overall, our findings show that plants grown outdoors contain higher secondary metabolites. In all cases, terpene potency was higher in outdoor plants. The un-targeted results show a trend toward a greater number of heavier oxygenated, sugar-conjugated compounds, like Orientin and Vitexin-2’-O-Rhamnoside, in the outdoor plants. THCa levels were also higher in outdoor plants in most cases.

Another interesting observation was specific strains in which genetics overcame the difference between indoor and outdoor grow environments. Two strains were found to be more impacted by genetics than by environmental conditions and showed less variability between indoor and outdoor than strain to stain. 

We also had limited data on heavy metal trends. Two plants grown indoors had some cadmium contamination whereas none outdoors did.

What does it all mean?

Growing environments undoubtedly have an effect on the product of cannabinoids, terpenes, and similar secondary metabolites. When deciding conditions for a cultivation, it is important to consider what kind of molecules you are interested in harvesting to create the best conditions for your plants to produce them. 

Stay tuned for more experiments on molecules like terpenes and heavy metals. 

Ready to start testing?

Testing with MCR Labs is fast and easy. Check out all the laboratories in our network!

Find a Lab
Cookies are used on this site and installed on your device to assist with page navigation, delivering content tailored to your interests, and for analyzing your use of our service to improve user experience. To learn about our cookies and your privacy, click here.