Caraway seeds should be harvested at the peak of their flavor. The plant matures in its second summer in temperate zones and in late spring in warmer climates. The leaves and roots of the plant can also be consumed. To harvest the seeds, wait until the flowerheads have turned brown and cut them off. Dry the flowerheads by suspending them upside-down or placing them on a cloth. After several weeks, check for dryness and then separate the seeds from the chaff through threshing. Finally, store the seeds in a cool, dark, dry location for up to four years.