"Why are we moving plants around?" Bret Roedemeier, senior director of cultivation and infrastructure at CLEANTheory, asked himself at a certain point in his career as a cannabis grower. "In traditional cultivation, you've got a veg room and a flower room," he explains. "That's based on the idea that growth does better under blue light of Metal Halide and flowering under orange light of High Pressure Sodium HIDs." When LED technology advanced enough to be utilized in commercial cannabis cultivation, the rules of the game changed, and Bret started questioning the old methods.
Why even
"Any controlled environment agriculture (CEA) situation—shock is the enemy," he remarks. "When you move plants from one room to another, you subject them to a certain degree of environmental stress, and they need time to recover from that." Plant growth stalls, and this kind of stress leads to shock, adds days to the veg cycle and impacts its ability to fully express its genetic potential.
As LEDs entered the picture, Bret realized something: when veg plants were grown entirely under full-spectrum LEDs, they grew just as fast and healthy without the need to switch rooms. "So why move plants around? That doesn't happen in nature. It all happens in one spot."
This simplified approach didn't just work on paper; it also brought practical benefits like fewer disease infections and improved overall production. "With the advent of LEDs, it allowed us to gradually bring plants into the cycle, avoiding shock. In nature, plants don't suddenly switch from 18-16 hours of light to 12-12 overnight, so we try to mimic what happens outside."
By eliminating the need for separate rooms, Bret's team saw a 12% increase in production over the year. Not only did they save labor—avoiding the need to move thousands of plants—but they also reduced plant stress. "Less handling means less stress, exposure to pathogens and that means better results," he points out.
Monocropping
While some cannabis growers cultivate multiple strains at once, Bret takes a different approach. He prefers monocropping. "One strain in one room—that's how I keep everything uniform. Same height, same water needs, same light requirements. You deal with fewer variables that way."
Automation plays a key role in his cultivation process, from fertigation and CO2 to HVAC systems. "We use Agrowtek, a PLC system with a robust sensor array. We spread out the irrigation cycle rack by rack, so we don't get humidity spikes. It keeps everything even."
For sanitation, Bret's team relies on CLEANTheory, a chlorine dioxide based injection system to combat mold and fungi. "When you're growing for Vapor Pressure Deficit (VPD) running high humidity and temperatures, you've got a real risk of mold. CleanTheory's System helps us stay ahead of that."
Preventing HLVd
In 2020, Bret first encountered Hop Latent Viroid (HLVd), a disease that significantly impacts cannabis plants. "Going forward, I use all tissue culture for my stock plants. We work with Conception Nurseries in Sacramento—they've got a great genetic library." Bret also introduced biosecurity measures like frequent disinfection and testing runoff for HLVd using technology from Medicinal Genomics. "Instead of testing each plant, we send off water samples from each rack. That way, we can isolate any infected plants without the high cost of individual testing."
Though tissue culture offers a solution to viroid infections, Bret notes the challenges of working within a limited genetic library. "You're limited to their library if you want something unique, it's good to mix in other breeders and their TC partners like Compound Genetics. They are pushing exciting exotics, with Node, their tissue culture partner." Even though Conception can ship around the country under the 2018 Farm Bill, Bret acknowledges that accessing a broader range of genetics for unique cultivars can still be a challenge.
Bret's isn't about keeping knowledge to himself. "I never believed in being a gatekeeper. I've always taught everything I know to my staff, because we're all gonna learn together." That open-source mindset extends to social media, where he regularly posts about common cultivation problems and shares photos of plant issues. "None of the stuff in my head is mine—I learned it from other people. I don't own it. At the end of the day, cultivation is about knowing a lot of little tricks, and some of them you've indeed learned from others. As an industry, we shouldn't keep those little tricks to ourselves; we should share them, just like traditional horticulture has been doing for centuries."
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