The herb Coriandrum sativum is a dual-purpose plant, offering two distinct flavors: the fresh leaves, known as cilantro, and the dried seeds, called coriander. The leaves provide a bright, citrusy accent to many cuisines, while the seeds offer a warmer, earthier spice profile. Successfully growing this plant at home requires understanding its preference for cool weather and managing its natural tendency to quickly transition from leaf production to seed production. This guide details the environmental necessities and cultivation techniques required to maximize your harvest of both cilantro leaves and coriander seeds.
Essential Growing Conditions
Coriander is a cool-weather annual that thrives when temperatures are moderate, performing best between 50°F and 85°F (10°C to 29°C). When conditions consistently exceed 75°F (24°C), the plant struggles, triggering it to “bolt,” or prematurely flower and set seed. This heat intolerance makes timing the planting important in warmer climates.
The plant requires full sun, meaning at least six hours of direct light daily. However, in regions with intense summer heat, providing partial afternoon shade is beneficial. This helps keep the plant cooler and delays the onset of bolting.
Ideal soil is loose, well-draining, and rich in organic matter, such as compost. Poor drainage can quickly lead to root rot, stressing the plant. A slightly acidic to neutral soil pH, typically between 6.2 and 6.8, supports the best growth.
Planting and Initial Care
Starting coriander from seed is the preferred method for home growers, as the plant develops a taproot highly sensitive to disturbance. Transplants often suffer from shock and are more likely to bolt quickly after planting. Seeds should be sown directly into the final growing location, either a garden bed or a container.
Plant seeds about one-quarter to one-half inch deep. If the goal is a leaf harvest, space seeds approximately 2 inches apart, with rows 12 to 15 inches apart to allow for air circulation. Once seedlings emerge and reach about 2 to 3 inches tall, thin them to a final spacing of 6 to 8 inches apart to prevent overcrowding.
If growing in containers, select a pot at least 8 to 10 inches deep to accommodate the taproot. Consistent moisture is necessary, especially during the germination phase, which typically takes 7 to 14 days. Water the soil deeply when the top inch feels dry, but never allow it to become waterlogged, as this is a common stressor that can cause bolting. Coriander is not a heavy feeder; a single application of a balanced, diluted liquid fertilizer once or twice during the growing season is sufficient.
Managing Growth and Preventing Bolting
The biggest challenge in growing cilantro leaves is managing its natural tendency to bolt when exposed to stress, most often caused by heat or drought. Once the plant bolts, the leaves become small and their flavor profile shifts to a bitter taste. Implementing cultural practices to keep the plant cool and unstressed is the strategy to delay this process.
Applying a layer of organic mulch, such as straw or shredded leaves, around the plants helps keep the soil temperature consistently lower and retains moisture. For container-grown plants, move them to a location that receives afternoon shade. In garden beds, using shade cloth or planting near taller crops provides natural shade during the hottest part of the day.
Succession planting is a technique that ensures a continuous supply of fresh leaves by sowing a small batch of seeds every two to three weeks. As older plants inevitably begin to bolt due to warming conditions, a new set of plants will be ready for harvest. Regularly harvesting the outer leaves also encourages the plant to produce new foliage rather than forming a flower stalk.
Harvesting the Leaves and Seeds
For a continuous supply of fresh cilantro, begin harvesting the leaves once the plant reaches about 6 inches in height. Focus on cutting the outer stems close to the ground, allowing the inner leaves to continue developing. Never remove more than one-third of the plant’s foliage at any single harvest, as excessive removal can stress the plant and cause it to bolt prematurely. Frequent, light harvesting encourages a bushier habit and delays flowering. Freshly harvested cilantro leaves can be stored in a glass of water on the counter or in the refrigerator for up to a week.
To harvest coriander seeds, allow the plant to complete its bolting process, which results in small, white or pinkish flowers that attract beneficial insects. After the flowers are pollinated, they develop into small, round seed pods.
The seeds are ready for harvest when they transition from green to a light brown color and feel dry and hard. Cut the entire stalk and place it in a paper bag or hang it upside down in a cool, dry, and dark location for two weeks to cure. Once fully dried, the seeds can be rubbed off the stalks and stored in an airtight container for up to three years.