10 Steps For Getting Seed As Clean As Possible

In my early seed-saving days, I’d thresh and I’d winnow but I just couldn’t get my seeds as clean as when those that came from a seed packet.

Over the next dozen years, meeting experienced seed growers, reading piles of seed production books, and attending whatever seed workshops I could find; I gleaned many pearls of wisdom that I then fine-tuned cleaning hundreds, if not thousands, of seed lots.

Here are the steps and lessons that have had the biggest impact in my seed saving career:

10 Steps For Getting Seed As Clean As Possible

  1. Make sure plant material is dry, dry, dry before threshing. In Eastern Canada, it can be hard to get a crop to dry in the field. Harvest whole plants when they are 3/4 dry. Spread them on tarps in a greenhouse with fans to increase ventilation and turn them periodically to ensure even drying.
  2. Leave dirt in the field. Leave dirty plant roots in the field when you harvest seed crops. It is much easier to not add dirt to your seed than to remove it later.
  3. Clean seeds on a dry day. Even if your seed crops are very dry, ambient humidity on an overcast or rainy will make seeds stick to the chaff.
  4. Thresh aggressively if seeds don’t easily shatter. Use boots, sticks, rakes, tractors, and trucks to shatter seeds from pods.
  5. Alternate screening and winnowing to blow away the light chaff and separate plant material into 2 groups:
    • Threshed seed and small bits of stem, pods, and rocks.
    • Larger plant material that contains unthreshed seed.
  6. Repeat steps 4 and 5 with larger plant material until you only have bins of threshed seed with small bits of stem, pods, and rocks that are the same size and weight.
  7. Winnow threshed seed aggressively to remove other material of similar size and weight.
  8. Screen seed carefully. Seed usually falls through first. Stop screening when most of the seed has fallen through.
  9. Be willing to sacrifice seed as you repeat steps 7 and 8. If you focus on getting seed clean rather than on saving every last seed, you can get seed a lot cleaner.
  10. Remove any remaining unwanted elements by hand. I usually spread seeds on a baking tray and do a final triage to remove broken and damaged seed, and any other remaining bits.

Seed saving examples

You can see all these principles in action in these two posts:

And in the next couple of posts I’ll demonstrate these principles for two crops that used to really give me a headache: radishes and lettuce.

Are there any tricks or lessons that really improved your seed saving?

2 thoughts on “10 Steps For Getting Seed As Clean As Possible

  1. I need to work on #9…getting those last few seeds always ends up as a waste of time.

    I do have a trick for lettuce, because our weather can be so wet and windy in the fall, and our lettuce never matures all at once, I often take a large pail into the garden and gently, without breaking the stem, tip the lettuce seed heads into the pail and banging them back and forth a few times allowing the seed that is ready to fall into the pail. This way I can quickly dispatch the seeds that are ready to be harvested while allowing the rest to continue maturing.

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