Saving Onion Seed
Sweet yellow onion 2nd year
Onions display a fair amount of inbreeding depression after two or three generations of self-pollination. Save and mix the seeds from at least two different plants.
Save seeds from non-hybrids, as hybrids are often unstable and breakdown. It's best to target heirloom crops for this. I save some seeds from hybrids that I have and use them only for bunching onions, as bulb size or long term storage isn't an issue.
Clip umbels or pull out the entire plant as soon as dried flowers begin to appear. I will usually grasp an inner flower from the center , which is still green or semi green and when it is cracked open, the Blackseed will emerge .
Fully dried flowers will drop clean seeds naturally. For small amounts, rub remaining flowers to free seeds. For larger amounts, rub heads over screens. Winnow to remove remaining debris.