The Winnow Wizard

Now in its final form after three seasons of continuing development and use at Wild Garden Seed, the Winnow Wizard is ready for prime time.  Designed in response to a need for precise density separations of small seed lots, it has already saved hundreds of hours and many thousands of dollars.  In addition to replacing manual fan winnowing, the Winnow Wizard has effectively removed dead or hollow seed from multiple low-germ lots, enabling sale of previously unsaleable seed.


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 splitters rest on ruled rails; the optimal setting for each seed type can be dialed in and repeated.
  • Two splitters and narrow bin can split the seed stream into three fractions: good, mixed (for re-winnowing or further processing), and trash.

Optional Accessories

  • Magnetic hopper gate: $95.  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.
  • Hopper agitator: $395.  Allows dirty, dusty, or papery seed to feed automatically from the hopper.  Very helpful if using the Wizard on seed lots that have not been field-winnowed.

Purchase a Wizard

Contact me if you are interested.  Each Wizard is custom built to order, tested with several types of seed, signed and dated, and adorned with original line art by Wild Garden Seed’s Victor Sauvie.  Cost (excluding shipping) is $1975, plus any accessories.

If you have a group of seed farms in your area that would like Winnow Wizards, I am available to travel, build on-site, and provide initial training.  Contact me if you are interested.

Build a Wizard

Unless you really enjoy tinkering and fabrication or you live outside the continental United States, I recommend purchasing a Winnow Wizard.  With multiple compound angles, <1/32″ tolerance on some dimensions, and many components to assemble, this is an advanced-level DIY project with high potential for frustration if things don’t line up correctly.

If you use the plans to build a Winnow Wizard, I ask that you send a photo and a check for $25 to Mark Luterra, 5175 SW Hillview Ave., Corvallis, OR 97333.  If you make alterations/improvements to the design, please send them to me for inclusion in the plans.

Documents (PDF)

Winnow Wizard principles, techniques, and operating manual

Plans and assembly instructions



Winnowing quinoa in the Wild Garden Seed greenhouse

Closeup of hopper opening and vibrating feed tray
Splitter set to remove small/light seed and chaff