For anyone who has been growing coriander that has now bolted, the flowers and seeds make wonderful ingredients in the kitchen. The flowers can be cut and sprinkled over salads and roasted squash, or over a bowl of daal or a curry dish – they have wonderful flavour, much like the leaves.
For the seeds, wait until they turn brown. The easiest thing to do then is to harvest the whole plant just before the seeds drop and put the entire plant into a brown paper bag. The seeds will then drop into the bag and it will be easy to extract the stems and rest of the plant so that you can store the seeds. Just pop them into an airtight container once they are fully dry.