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

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

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.

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

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.

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

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.

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

Guest: Julie Graesch
Biological Scientist | IPM Specialist
Currently with BioWorks
Formerly: BASF, Becker Underwood, Iowa State University

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

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

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

n this conversation with plant scientist and commercial cultivation strategist Dr. Matthew Indest, we explore the emerging frontier of seed-based cannabis production and what it would take for the industry to move beyond clonal propagation.

We cover:

The agronomic upside of seed-grown plants (disease resistance, vigor, adaptability, cost savings)

The scientific and operational barriers preventing widespread seed adoption

How genetic stability, inbreeding depression, and trait selection differ between cannabis and traditional crops

Data-driven cultivation strategies for evaluating new seed lines

Whether seed-based production can truly rival clonal systems for consistency and top-tier flower quality

What the next decade of cannabis breeding and cultivation might look like

About Dr. Indest:
Matthew holds a Ph.D. in plant science and has spent more than a decade bridging academic research with applied cannabis production. He has led breeding and cultivation programs across indoor, greenhouse, and outdoor operations and focuses on developing high-performing cultivars and integrated, data-backed production systems.

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

This wide-ranging conversation with Bryant Mason covers a series of essential—but frequently misunderstood—topics in organic cultivation. We explore why simple, low-tech data collection strategies often outperform high-tech systems and how to interpret those readings in the real world. From there, we break down how pH truly behaves in biologically active soils, what your water test results do and don’t tell you, and how water chemistry shapes nutrient availability.

We also discuss practical considerations for under-canopy lighting, when it helps and when it’s a distraction, and dig into the recurring challenges Bryant sees around phosphorus and nitrogen management in living soil. Throughout the episode we jump between concepts, case studies, and troubleshooting insights that growers can apply immediately.

Topics Covered:

Low-tech monitoring and data-collection approaches

pH dynamics in organic systems

Water testing and interpreting results

Under-canopy lighting: pros, cons, and real-world use

Phosphorus and nitrogen management in living soil

Practical troubleshooting and decision-making strategies

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.

In this conversation, Tad and Dr. David Hawley (Chief Science Officer at Fluence) unpack what really matters when dialing in your lighting strategy for cannabis and other high-value crops. They get deep into how plants perceive light, what “good spectrum” actually means, and how to think about intensity, uniformity, and plant response in a more scientific (and practical) way.

Topics covered include:

Understanding Daily Light Integral (DLI) and how it relates to plant metabolism

When to use far-red and what to expect from it

The truth about UV lighting and secondary metabolite production

Managing leaf temperature and avoiding hidden stress from high PPFD

How fixture placement and uniformity impact yield and morphology

Using dimming strategies through different growth stages

Why overemphasizing spectrum specs can distract from the real gains

Practical steps for mapping your grow and verifying performance

David also shares insights on under-canopy lighting, canopy architecture, and the future of horticultural light design, offering takeaways for both commercial cultivators and serious home growers.

Resources mentioned:

Fluence by OSRAM

KiS Organics Living Soil & Nutrients

Hosted by Simplecast, an AdsWizz company. See pcm.adswizz.com for information about our collection and use of personal data for advertising.