Cilantro is the fresh leaves and stems of Coriandrum sativum; coriander is the dried fruit (seeds). When the plant “bolts” by producing a central flowering stalk, it transitions from a leafy herb crop to a spice crop. Completing this life cycle allows for the harvesting of aromatic seeds. Saving the seeds ensures a supply of homegrown coriander and allows for future planting.
Identifying Mature Seed Heads
Harvest timing is determined by visual and tactile changes. Initially, the small, round seeds are bright, lime-green and soft. At this immature stage, the flavor is sharp and bitter, and the seeds lack viability. The plant must fully mature the seeds on the stalk to develop the characteristic warm, earthy, and citrusy flavor of coriander.
As the seeds ripen, they progress from green to a pinkish-tan hue, eventually drying to a light brown or beige color. This color change signals that the moisture content is dropping, indicating maturity. Harvest is ideal when the majority of the seeds are brown and dry, before they shatter and drop. A ready seed feels hard and dry when rubbed between the fingers.
Harvesting and Initial Curing
To prevent the loss of mature seeds, harvest the stalks when approximately 75% of the seeds on the umbel have turned brown. Use clean shears to cut the stalk near the base. Harvest in the early morning while the air is cool and damp, as this minimizes the risk of brittle seeds shattering.
The harvested stalks must undergo curing to ensure remaining green seeds fully dry and develop flavor and viability. Gather the stalks into small bundles and secure them with twine or a rubber band. Hang these bundles upside down in a cool, dry, and well-ventilated location, such as a garage or shed.
To capture falling seeds, place a tarp, bucket, or large paper bag beneath the bundles. Alternatively, place the seed heads into a large paper bag and tie it loosely around the stem to create a self-contained drying unit. This curing process usually takes one to two weeks, until the stems are completely brittle and dry.
Separating and Storing the Seeds
Once the stalks are cured and brittle, the seeds must be separated from the stem material and chaff through threshing and winnowing. Threshing breaks the seeds free from the umbels. This is done by rubbing the dry seed heads between your hands over a container or by placing the bundle inside a cloth bag and gently beating it.
Threshing results in a mixture of seeds, stem fragments, and light chaff. Winnowing separates the heavier, viable seeds from the lighter debris. Pour the mixture slowly from one container to another in front of a gentle air current, such as a light breeze or a small fan. The air carries the lighter chaff away, allowing the heavier seeds to fall into the catch container.
Before storage, ensure the seeds are completely dry to prevent mold and preserve viability. Store the clean coriander seeds in an airtight container, such as a glass jar, away from direct sunlight, heat, and humidity. Properly stored seeds maintain viability and flavor for two to three years.