The Winnow Wizard

Developed at Wild Garden Seed and now in use at seed companies across the United States and Canada, the Winnow Wizard is a game-changer for small-scale seed production.  In addition to replacing manual fan winnowing, the Winnow Wizard can perform precise density separations to remove hollow/immature seeds, difficult chaff/weed seeds, and heavier dirt/rocks.  It has saved thousands of labor hours and many thousands of dollars – both through time savings and through bringing unsaleable lots up to acceptable germination rates.


Inspired by the sterile laminar flow hoods in my microbiology background, the Winnow Wizard uses a pressure differential across a series of perforated metal grates to create a steady, even, adjustable flow of air.  By changing grates and varying blower speed, airflow can be adjusted from a gentle breeze for tiny yarrow and snapdragon seeds up to a strong wind for brassicas, corn, and beans.

In contrast to fanning mills, air separation occurs in a visually open area allowing for continuous monitoring and adjustment during operation and eliminating the potential for seed contamination between lots.  As a precision density separator, the Winnow Wizard performs many of the same functions as a gravity table at a fraction of the cost with no minimum lot size, no cleanout time, and simple, intuitive adjustments.

Following the model of the Open Source Seed Initiative, this is an open source design.  I do not intend to seek a patent, and publication of the plans online legally precludes any other entity from patenting it.


  • Wide adjustable range of wind speeds for seeds of all types.
  • Vibrating feed tray with adjustable angle and slot width for different seed shapes and sizes.
  • Hopper holds up to 12 gallons of seed, with sliding gate for slow-feed, accurate winnowing or fast-feed, rougher winnowing.
  • Hopper support (along with hopper and feed tray) easily removed for manual pouring of very small lots or non-flowing seeds.
  • Seed dividers rest on ruled rails; the optimal setting for each seed type can be dialed in and repeated.
  • Two dividers and narrow bin can split the seed stream into three fractions: good, mixed (for re-winnowing or further processing), and trash.
  • Hopper agitator allows dirty, dusty, or papery seed to feed automatically from the hopper.
  • Magnetic hopper gate (optional) uses powerful rare-earth magnets to deflect dirt and rock particles out of a falling stream of seed.  Works best with small seed, and efficacy may vary with magnetic properties of local soil.

Purchase a Wizard

After building 105 Winnow Wizards by hand in the Wild Garden Seed shop, I have handed off manufacturing to the skilled manufacturing team at Oppen Works in Viroqua, WI.  All Winnow Wizards now ship with a 1 HP blower for better separation of large seeds, although the airflow can still be adjusted to a gentle breeze for the smallest flower and herb seeds.

To place an order for a Winnow Wizard, please visit the Oppen Works website.  For questions regarding potential applications, functionality, and shipping, please email me.


Oppen Works (2023+) Winnow Wizard (1 HP) techniques and operating manual (PDF).

Winnow Wizard (3/4 HP, 2016-2022) techniques and operating manual (PDF)

Manual de operacion – Español (3/4 HP, 2016-2022) (PDF)

Winnow Wizard (1 HP, 2018-2022) techniques and operating manual (PDF)

Setup, operation, maintenance, and troubleshooting.  Detailed descriptions of winnowing techniques to remove chaff, hollow/immature seed, and material heavier than seed.  Probability-based techniques for winnowing flat seed.  Instructions for hopper agitator and magnetic dirt removal.

Seed cleaning strategies (PDF)

Overview of the seed cleaning process used at Wild Garden Seed, with complete process descriptions for kale and lettuce seed.  Discussion of the advantages and limitations of winnowing, and how best to combine winnowing and screening steps to clean seed efficiently.  Listing of useful screen sizes for common vegetable seeds.  Table of screens and Winnow Wizard settings across a wide range of seed sizes.  Summary of ways in which the Winnow Wizard has streamlined and improved seed cleaning at Wild Garden.


The Dendroica Project on Substack is a collection of my writings on themes of ecological spirituality, embodiment, and connection to land and place. New essays and poems are published on the 21st of each month and occasionally more often.

Selected writings:

  • The Dendroica Project: An Introduction – an explanation of the name and the overarching theme.
  • Blessed Rain – a poem from 2020 inspired by the return of autumn rain after a month of massive fires.
  • Musings on the Ever Given – a poetic exploration of the hidden beauty in our global economy obscured by bland capitalism and how we might re-envision our webs of connection and exchange.
  • Hymns for an Ecological Spirituality and A Solstice Songbook – collections of sacred and meaningful songs celebrating rootedness and belonging on Earth.
  • April Showers (and Other Everyday Miracles) – a poetic exploration of spring rain and photosynthesis and flowers and seeds.
  • Gratitude – a Thanksgiving reflection on all that I am thankful for.
  • Gazing Outward – musings on galactic scale and my complete lack of desire to be an astronaut.
  • Poetry of Belonging – introducing the powerful poetry of Hannah Elizabeth King.
  • On Control and Participation – a critique of some well-meaning efforts that are still based upon a mentality of dominion and separation.
  • Two Worlds – a poetic contrast between the linear environments we create and the entirely nonlinear environments that exist within our bodies and beyond our interventions.
  • Denaturing Duality – a philosophical exploration of the assumed passivity of “nature”, and a critique of the judgments we attach to “natural” and “synthetic”.
  • Lifeblood – a re-enchantment of the hydrologic cycle.

Parallel projects – from other writers whose words resonate with my own

  • We Are Wanderers – a debut book from local poet Hannah Elizabeth King, whose words helped to catalyze a deep healing and reconnecting and grounding within myself.
  • the heart of Gaia – musings on the wonder and mystery of our embodiment on Earth from Kate Clearlight.
  • Tales of the Hedgewise – essays “woven with the threads of folk herbal wisdom, animism and storytelling, in the ways of the heart” from Marija Petkovska


My name is Markael Luterra.  This website is a portfolio of my designs, ideas, and knowledge, and writings.  I don’t wish to convince you to buy anything you don’t need.  Rather, I wish to offer solutions that have worked for employers, clients, and my own endeavors.  Suggested improvements are welcome.

I have never managed to fit conveniently into a category.  As a child in rural southwest Minnesota, my passions cycled between gardening, biology, botany, astronomy, weather, natural history, music, conservation, engineering, and alternative energy.

I pursued conservation biology through a BA at Carleton College (2007).  As education transitioned to career, I began to feel that I could not value the warblers, the prairie flowers, the seasonal cycles as I wished when assessing them as data points, and the engineering side of me wished to solve problems rather than simply understand them.

Following an idea for bio-solar hydrogen production, I completed a Ph.D. in Biological and Ecological Engineering at Oregon State University in 2014.  Though my work redesigning the metabolic pathways of cyanobacteria to convert sunlight to hydrogen energy was largely a success from an academic perspective, I began to question the cultural mythology that new technology will bring a shiny future of space travel and unlimited energy.  I wasn’t sure that I wished to inhabit that future, even if it were possible.  Caught in an artificial world of pipettes, sterile hoods, and centrifuges, growing re-engineered cells under fluorescent lights, I wished to return to working alongside the myriad creations of three billion years of evolution.

From 2014-2022 I worked for Wild Garden Seed, an organic vegetable and flower seed company driven by the passion and plant-breeding creativity of owners Frank and Karen Morton.  Many of the designs offered here were created to solve problems and increase efficiency in the Wild Garden operation.  Since 2023 I have worked for Adaptive Seeds and contracted for Ten Rivers Food Web in addition to working toward the development of a food hub in my hometown.

My goal in offering these designs and services and essays is to help envision and build and inhabit sustainable, soul-nourishing communities – communities where seeds, produce, equipment, and the “stuff” of life are supplied not by multinational corporations via big box stores but rather by friends, neighbors, family businesses, and cooperatives.  I welcome opportunities to collaborate with others who share this vision.


Luterra Enterprises LLC

Markael Luterra, Ph.D.

Corvallis, OR