Cilantro (Coriandrum sativum) is an annual herb that provides both leaves and seeds for the kitchen. Cilantro seeds are called coriander. Growing 18 to 24 inches tall and 12 to 18 inches wide, cilantro thrives in sunny spots and medium-moisture, freely draining soil. Cool, dry summer climates provide the best cilantro crops, as this plant doesn't tolerate high humidity or frequent rain. In hot summer climates, providing some light afternoon shade helps cilantro grow well. Harvesting takes place when the plants or seeds are mature.
Cilantro leaves are ready to harvest when the leaf stems are about 4 to 6 inches long. In good growing conditions, this is usually 45 to 70 days after sowing.
Cilantro leaves are divided into leaflets that branch from central stems. Stems cluster at the plant bases, forming clumps. You can harvest single stems, or whole clumps. Harvesting cilantro clumps provides large and small leaves. After harvesting cilantro clumps, the plants may resprout and produce more leaves.
Harvesting Cilantro Leaves
Pruning shears or scissors are best for harvesting cilantro leaves. Sterilizing pruning shears or scissors before and after harvesting cilantro helps prevent pests and diseases from spreading.
Wipe pruning shear or scissor blades with a cloth that was dipped in rubbing alcohol, and snip cilantro leaf stems at their bases. If harvesting cilantro clumps, snip through all the stems 1 to 2 inches above soil level. Wipe the pruning shear or scissor blades again when you've finished.
Extending the Harvest
Removing flowers and repeated sowing extends the harvesting period for cilantro leaves. As an annual plant, cilantro dies after setting seed. Preventing seed development by removing flowers encourages the plant to continue growing. Remove cilantro flower stems before the flowers open by pruning the stems at their bases.
Through the growing season, sow cilantro seeds every two weeks to extend the harvest. You can sow cilantro seed up to late summer for a crop of leaves, but the plants won't produce seed before the first local average frost date in most areas of the United States.
Harvesting Coriander Seeds
Cilantro produces seeds in late summer and early fall, about 90 days after sowing. If growing cilantro for coriander seeds, don't harvest the plant's leaves.
Cilantro flowers are white, pink or pale lavender, and they naturally form yellow-brown seed pods after pollination. In late summer or early fall, when the plants turn brown, prune the seed heads with sterilized pruning shears or scissors. Snip the seed pod stems at their bases, and place them in paper bags. Hang the bags in cool, dry, airy places until the stems wither and the seeds drop out of the pods.