Cannabis Cultivation and Science Podcast

Key Takeaways:

Botany vs. Hacks: Moving past "quick fixes" to understand the biological lens of plant science.

The Limiting Factor: Learning to identify the specific environmental or nutritional gaps holding your plants back.

Timeless Principles: Why botanical fundamentals are the most reliable tools in a cultivator’s shed, regardless of changing trends.

Applied Horticulture: Bridging the gap between academic theory and high-level landscape maintenance.

About Don Marshall: Don is a Certified Professional Horticulturalist, Certified Arborist, and ecoPro. He founded the Environmental Horticulture program at Lake Washington College, where he taught for over 40 years. He is the owner of Plant Designs, a fine gardening firm, and the co-author of Home Landscaping, Northwest Region.

The Botany Foundations Course: Don and I have spent the last few years collaborating on a comprehensive online botany course. We designed this specifically for industry professionals and serious growers who want a university-level understanding of plant science without the time constraints of traditional schooling. This course provides the professional lens needed to evaluate and improve your grow.

Stay Updated: www.kisorganics.com

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The Underground Economy: Carbon as Currency

Biological Gold: Why photosynthesis isn't just about plant growth—it’s about minting the "carbon currency" required to hire a microbial workforce.

The Exudate Menu: A breakdown of Monosaccharides (fast cash), Polysaccharides (savings accounts), and Organic Acids (specialized mining tools).

The Trading Post: How the plant uses targeted "buy orders" to trade energy for the specific minerals it needs.

The Rhizophagy Revolution

The "Commuter" Microbes: Understanding the research from Dr. James White’s lab at Rutgers.

The Microbial Car Wash: A technical look at how plants lure, strip, "milk," and eject bacteria to scavenge for nutrients.

Endophytes vs. Rhizophagy: Distinguishing between long-term "tenants" inside the plant and the transient "workers" in the root tip.

The Biomimicry Reality Check

Ecology vs. Agronomy: Why nature optimizes for survival, while growers optimize for yield, quality, and consistency.

The Managed System: Why an indoor grow or greenhouse is not a wilderness, and why treating it as such often leads to inefficiencies and "natural" bottlenecks.

The "Selfish" Microbe: Understanding Immobilization and Stoichiometry—why microbes sometimes "rob" your plants of nitrogen to build their own populations.

Precision Biology & Biosecurity

The Risk of Raw Inputs: Why compost can be the highest risk factor for heavy metals, PFAs, herbicide residues, and pathogens like Pythium.

The Specialist Shop: Utilizing lab-grown consortiums for a cleaner, scalable facility.

Mycorrhizal Fungi: The role of Rhizophagus irregularis in Phosphorus mining.

Nutrient Unlockers: Using high-CFU strains like Microbial Mass or Mammoth P for data-backed biomass increases.

Trichoderma: Beyond biocontrol—how it uses siderophores to "magnetize" insoluble iron and trigger Induced Systemic Resistance.

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This episode is part of the Foundations of Soil & Plant Science series — a selection of conversations that continue to influence how I approach soil health, plant performance, and cultivation systems. I’ve added a short new intro to each re-release with updated perspective and context.
Originally released as Episode 20
My guest for this episode is Ben Hartman, farmer and author of The Lean Farm.
Ben operates Clay Bottom Farm in Goshen, Indiana, and is known for applying lean manufacturing principles to agriculture. His work focuses on improving farm efficiency, reducing wasted time and materials, and designing production systems that prioritize value and profitability.
In this conversation we discuss:
What lean farming means and how it applies to cultivation
Identifying and eliminating wasted time, labor, and inputs
Designing efficient workflows and production systems
How simplifying systems can improve consistency and profitability
Applying lean principles to indoor and greenhouse cultivation
While this conversation comes from outside traditional cannabis production, the principles discussed are directly applicable to any cultivation operation looking to improve efficiency and long-term sustainability.
Part of the Foundations of Soil & Plant Science series.

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My guest for this episode is Dr. Wendy Zellner.
Dr. Zellner received her doctorate from the University of Toledo in 2012, where she trained in molecular and cellular biology with a focus on the role of silicon in plant defense responses. She then completed a four-year postdoctoral position with the USDA-ARS, continuing her research on how silicon can alleviate both abiotic and biotic stress in crops such as tomato and tobacco.
Her work has included developing standard methods for quantifying silicon uptake from fertilizer materials, identifying uptake mechanisms for silicon in model species, and evaluating how those pathways function across a range of crop systems.
In this conversation we cover:
The role of silicon in plant physiology and structure
Silicon and plant defense against abiotic and biotic stress
How plants take up and utilize silicon
Misconceptions around silicon fertilizers and supplements
Practical considerations for growers using silicon inputs
This remains one of the most comprehensive discussions we’ve had on silicon and plant health, and it continues to be highly relevant for growers looking to better understand how this element functions within a complete fertility program.

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Guest: Julie Graesch
Biological Scientist | IPM Specialist
Currently with BioWorks
Formerly: BASF, Becker Underwood, Iowa State University
Topics Covered:
What “entomopathogenic fungi” actually means
How fungi like Beauveria and Metarhizium infect insect pests
Differences between blastospores and conidia
Why formulation and environmental conditions matter
Common reasons fungal biocontrol applications fail
Preventative vs. reactive use of entomopathogenic fungi
Integrating fungal biologicals into a broader IPM strategy
Key Takeaways:
Entomopathogenic fungi are biological tools, not chemical knockdowns
Understanding fungal life cycles improves consistency and outcomes
Blastospores behave differently than traditional spore formulations
Successful IPM relies on timing, environment, and integration—not rescue sprays

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