I figured out on my own how to clean the seed- mostly.

I had the seed in a small sherbert tub. While shaking the tub gently, I blew and blew to blow the chaff out of the tub. It left quite the mess on the kitchen table to clean up, but it got most of the chaff out while leaving the seed in the tub.

Whole process took about a half hour of blow while shaking, sweep chaff off, and blow some more.

That is a really great effort I must say. I have tried myself before to clear off the chaff from the seeds but I thought it was too tedious a process so I decided to let them be instead of wasting time and effort doing it manually. I would rather let nature takes its own course. As for me, I would gladly just buy new seeds if I wish to plant new toothache plants.

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I don't bother to clean the seeds for spilanthes, storing the dried seedheads whole. When I'm ready to plant, I simply crumble the seedheads & scatter over the area I want to plant.