How to Grow and Harvest Coriander
Harvesting is simple. You wait until the plant is completely dead, dry and brown and the little seeds have taken the place of the little white flowers. You shake the seeds off (I used a large bucket), wash them and dry them thoroughly. I used a small colander.
The most important thing is to get them very, very dry before storing, and the most annoying thing is removing all the little bits of chaff, or dead plant bits. Of course some "dried cilantro" bits aren't going to hurt you any when you grind up your coriander seeds, so I fished about 90% out and then left the rest of the tiny pieces in. No biggy.