The Winnow Wizard


After a year of winnowing in front of fans, behind fans, and in inconsistent breezes, I wanted to improve the accuracy of the process.  I couldn’t find a precision winnower design, so I decided I would try to invent one.  I had previously worked in a microbiology lab and was familiar with “laminar flow hoods” that used a pressure differential across a filter or grate to produce an even flow of sterile air.  Applying that principle in a horizontal wind tunnel I was able to create an adjustable, steady, even airflow for winnowing.  The design changed substantially from the first prototype to the second, with a few more refinements from the second to the third, pictured above.  At Wild Garden Seed, the Winnow Wizard has cut our seed cleaning time approximately in half, and it has enabled us to remove slightly-lighter immature seeds to bring low-germ seed lots up to acceptable germination.


  • Multiple-speed blower and three screen slots in the wind tunnel allow for a wide range of wind speeds, for everything from the lightest flower and lettuce seed up to dry beans and corn.
  • 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 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.

Purchase a Wizard

Contact me if you are interested.  Let me know the length and height of your intended receiving bins.  The standard version works with Sterilite (15.5″ height) and tall Rubbermaid (16″ height) bins.

Buyer pays freight shipping from Corvallis, Oregon.  I can deliver (with mileage reimbursement) up to 250 miles.  Local pickup is also an option; a Winnow Wizard will fit in a pickup with a 6′ bed.

Each Wizard is custom built to order and requires roughly $750 in parts and 30 hours of fabrication time.  Cost (excluding shipping) is $1975.

Build a Wizard

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.  If you make improvements to the design, please send them to me for inclusion in the plans.

If you have a fabrication facility and wish to build Winnow Wizards for sale, I would appreciate a voluntary royalty arrangement.

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 can source a good used blower, cost will be around $500 for parts plus 30-40 hours for construction.  A new blower will run $230-$300 plus shipping, depending on source and desired HP rating.

If you have a group of seed farms in your area that would like Winnow Wizards, I am available to travel and guide construction/implementation.  Contact me if you are interested.  Cost is my travel expenses plus a negotiable per-diem rate.

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.


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