First things first -- let those plants BOLT! They look ugly, but to make seed, they need to stop the growth process, get brown and ugly and shrivel up.
Collect your bunches of plants, seedpods intact and haul them up to the porch to dry a little further.
Use dehydrator or hanging them from the rafters of a dry barn or porch works just as well!
If you are working in a smaller space, you can snip off the seedpods (see that little brown bugger out there?) and let them dry on a flat screen or a dry glass bowl. The seedpods will pop right open with a little pressure from your thumb when they are "ripe".
When you get to that point, you are ready to separate the seed from the chaff! Crack open the pods into a bowl of water, allowing the seeds to drop to the bottom and the other bits to float to the top.
Skim the little bits off the top, then pour through a towel lined colander.
You might have to do this one or two times to get the seeds separated. Once the seeds are separated, let them dry a little while longer until they rattle around freely in a glass jar.
The next step?
- Grind your seeds for powdered spices (mustard, cumin, etc.)
- Dry them for planting next year
- Dry them to use in a spice grinder as you cook
- Add them to pickling liquids, vinegars and flavored oils