Cilantro and coriander are two names for the same plant, Coriandrum sativum. Cilantro refers to the fresh leaves, while coriander is the name given to the plant’s dried seeds used as a spice. To successfully harvest the seeds, the plant must be allowed to fully complete its natural life cycle after the leafy stage has concluded. The process involves precise timing and handling to ensure the seeds are mature, flavorful, and ready for use.
Allowing Cilantro to Transform
The shift from leaf production to seed production is a natural process for the cilantro plant, known as bolting. This transition is triggered by environmental factors, primarily rising temperatures (especially when the weather consistently exceeds 75°F) and increasing daylight hours. The plant responds by rapidly growing a tall, thick central stalk.
As the plant bolts, its energy diverts away from the broad leaves, causing the remaining foliage to become feathery and less desirable for consumption. Delicate flowers, usually white or pale pink, develop at the top of the stalk, attracting pollinators. Once pollination occurs, these flowers fade, and small, round, green structures begin to form, which are the immature seed pods.
This green pod stage represents the preliminary phase of seed development. The seeds are still soft and hold a different, brighter flavor profile than the mature spice. Waiting for the seed pods to progress past the green stage is necessary for harvesting the dried spice, coriander.
Determining Seed Readiness
The timing for harvesting coriander seeds is determined by distinct visual and tactile cues, which signal the end of the maturation process. The seeds must transition completely from their initial green color to a pale brown, light tan, or gray hue. This color change indicates that the seed has finished accumulating starches and oils and is beginning to dry out.
A gentle squeeze test on the seed heads should reveal that the seeds are firm and dry, not soft or moist. If the seeds are harvested too early, they may lack the characteristic nutty, citrus flavor of coriander and will not store well. Waiting too long can result in significant loss due to shattering, where the seeds drop from the plant as soon as they are fully dry.
The optimal time to cut the entire stalk is when approximately 50 to 70% of the seeds on the cluster have turned the characteristic brown or tan color. Harvesting at this point allows the slightly greener seeds to finish maturing off the plant during the curing process. This preemptive harvest minimizes the risk of losing the earliest, fully mature seeds that are already loosely held on the plant.
Harvesting and Curing the Seeds
Harvest should take place on a dry, clear day, preferably in the mid-morning after any dew has evaporated. Using sharp shears, cut the entire stalk close to the ground, handling the plant gently to prevent premature seed loss. Since the seeds are prone to shattering, place a container or cloth beneath the plant while cutting.
Immediately after cutting, bundle the stalks together for curing, which is the process of drying the seeds completely. The bundles should be hung upside down in a warm, dry, and well-ventilated area, such as a garage or shed. Proper ventilation prevents the buildup of moisture, which could lead to mold development.
To capture any seeds that fall during the drying period, suspend the seed heads inside a large paper bag tied securely around the stems. The curing process typically takes between one and three weeks, depending on the location’s temperature and humidity. The seeds are ready to be fully separated when they easily detach from the stem and the plant material is completely brittle.
Preparing Seeds for Storage
Once the stalks and seeds are fully cured, the final step involves separating the seed from the remaining plant material, known as chaff. This is accomplished by lightly threshing the dry seed heads—gently crushing or rubbing them over a clean surface or into a container. Release the seeds from the umbels without cracking or damaging them.
After the initial threshing, the mixture of seeds and chaff needs to be cleaned to isolate the spice. Blowing lightly across the mixture or using a fine-mesh sieve separates the heavier seeds from the lighter, discarded plant fragments. Confirm that the seeds are entirely dry before moving to storage, as any residual moisture can lead to mold or spoilage.
For long-term storage, place the cleaned, dry coriander seeds in an airtight container, such as a glass jar. Storing the seeds whole, rather than ground, helps preserve their volatile oils and flavor for a longer period. The container should be kept in a cool, dark location away from direct sunlight and heat to maintain the seeds’ quality for future culinary use or planting.