Evening Primrose

I have several plants of evening primrose. Can you tell me what part of the plant is used and how it is harvested. And also is there a market for it?

The seeds yield an oil which contains gamma-linolenic acid, a fatty acid essential to humans. It has an effect on many bodily functions. It is used to treat such conditions as PMS, heart disease and high blood pressure. The book, "Evening Primrose Oil" has a lot of information on how to use the oil.
The seeds can be gathered anytime after the seeds ripen (turn brown). Small quantities can be harvested by hand. On commercial farms it harvested by machine, usually with a combine.
There is a market for it, but only in large quantities. Commercial growers are growing it in the tonnes. John Baker, who developed some of the commercial varieties grown today, gave a detailed presentation on commercial production of evening primrose at the Second Richters Herb Growing Conference. The transcripts can be ordered online at our website.