Home Threshing & Winnowing Seed
Lots of seed comes in pods, or with feathery bits attached.
Usually stomping on the dry seedpods will break it all up & release the seed,
but then how do you get rid of all the bits?
Often the answer is to winnow. Because the bits are lighter than the seed, they blow away in a breeze.
Harvest . . .
So, you've decided its time to harvest. Cut the whole stem off, and pile on an old sheet somewhere airy (and bird-free - they love the seed) to dry.
...Thresh . . . .
Once dry, jump all over them and you'll get lots of seed mixed with broken up stem & pods.
For things like oats and chard that have tough glumes or are well-attached to the stems, a great trick is to stomp and stamp it on a rubber mat. The rubber grips the plant material but is soft enough to stop the seeds being damaged.
So you've got this pile of stems and stalks and seeds - shake the pile & the seeds will fall to the bottom, and you can just pull off most of the big bits of rubbish now.
Sieve if you can
If you have a garden riddle – you know, a round wooden sieve for sieving compost- it can sometimes help to pour the mixed seeds & debris through it, to get out the bigger bits of rubbish. If not, just pick them out by hand.
Putting the lot in a bucket and tapping it works well too – the bigger bits rise to the surface and can be picked out. Just be patient. You need to get out any big bits simply so it dries well. Large bits of stem or leaf never dry properly, and are an invitation to damp and mould in storage.
Then to get the rest out, pour the seed and bits from one bucket to another in a breeze - the bits will blow away, and the seed will remain.