Episode 165: Boosting Yields 50% with a 13-Hour Photoperiod? Debunking Cannabis Science with Dr. Youbin Zheng
Can a simple 1-hour change to your lighting schedule increase your flower yields by 50% and your THC by 9%? On this week’s episode of the Cannabis Cultivation and Science Podcast, host Tad Hussey sits down with leading horticulture professor Dr. Youbin Zheng from the University of Guelph in Ontario, Canada.
Dr. Zheng is a principal investigator at the absolute forefront of high-THC cannabis agronomy and the author of the definitive textbook, Handbook of Cannabis Production in Controlled Environments.
Drawing directly from peer-reviewed data conducted inside commercial licensed facilities, Tad and Dr. Zheng smash some of the industry’s most deeply rooted legacy myths. They dive into why heavy phosphorus feeding is reducing your profits, the surprising truth about how modern high-THC genetics react to supplemental UV light, and the exact science behind using controlled deficit irrigation to trigger a late-flower cannabinoid spike.
Whether you are managing a large-scale commercial facility or navigating a boutique organic living soil bed, Dr. Zheng’s pragmatic, data-first approach offers actionable insights to dramatically optimize your canopy’s ROI.
In this episode, we discuss:
Bridging the Genetic Gap: Looking critically at how horticultural research transfers between high-THC cultivars and industrial hemp.
The 13-Hour Photoperiod: Breaking the traditional 12/12 cycle to achieve a 39%–50% yield increase and a 9% THC boost.
Linear Light Scaling: The direct relationship between light intensity and flower yield scaling all the way up to 1,800 micromoles under ambient CO2.
The UV Reality Check: Why modern high-THC genetics actually showed a decrease in final cannabinoid and terpene content under supplemental UVA and UVB.
Light Response Curves: Why relying on a single leaf measurement to guide your facility's light saturation point is fundamentally flawed.
The Veg-to-Flower Transition: Practical SOPs for adjusting PPFD and DLI safely without shocking your canopy.
Controlled Deficit Irrigation: How a single, targeted late-flower drought stress event triggers a 12%–13% spike in final THC and CBD content.
The 60 PPM Phosphorus Rule: Looking at the established replication data proving that excess phosphorus wastes money, reduces yield efficiency, and impacts the environment.
Links & Resources Mentioned in This Episode:
Visit KIS Organics for commercial living soils, amendments, and consulting: https://www.kisorganics.com
Grab Dr. Zheng's textbook, Handbook of Cannabis Production in Controlled Environments: https://www.amazon.com/Handbook-Cannabis-Production-Controlled-Environments/dp/0367712571
Access Dr. Zheng’s open-access research papers on Google Scholar: https://scholar.google.com/citations?user=ciGdnWAAAAAJ&hl=en
Connect with us on Instagram: @kisorganics
