Collecting viable seed from globe artichokes takes patience and an understanding of when the plant is ready. Artichoke seeds only develop after the flower is fully mature, so timing is critical.
To harvest, allow some artichoke flower heads to remain on the plant rather than picking them for eating. As the flower blooms and dies back, the head will swell and dry out. Once the petals have dropped and the head begins to fluff up with downy material, the seeds inside are ready.
Cut the dried flower head from the plant using secateurs. Place it in a paper bag or tray and allow it to finish drying in a cool, airy place. When fully dry, break the head open and rub or shake it apart to release the seeds. Separate the small, dark brown seeds from the fluff and discard any that are light or misshapen.
Artichoke seeds are generally ready to harvest towards the end of summer or early autumn, depending on when the plant flowered. In most parts of the UK, this means from late August through September. Only harvest once the flower head is completely dry and beginning to disperse fluff — seeds collected too early will not be viable.