The herb Coriandrum sativum provides two popular ingredients: the leaves, known as cilantro, and the seeds, known as coriander. This annual herb is a staple in global cuisines, lending a fresh, citrusy flavor to dishes worldwide. Growing coriander from seed is straightforward but requires understanding the plant’s preference for cool weather to ensure a long, productive harvest. The goal is to maximize leaf production before the plant naturally shifts its energy toward seed production.
Site and Soil Preparation
Coriander is a cool-season crop that thrives when temperatures are moderate, ideally between 50°F and 75°F. Plant in early spring after the last frost or in late summer/early fall when the harsh heat has passed. In hot climates, choose a location that receives full morning sun but offers partial shade during the intense afternoon heat.
The plant requires loose, well-drained soil to prevent the taproot from rotting, as it dislikes waterlogged conditions. Avoid heavy clay soil or amend it significantly by incorporating two to four inches of well-composted organic matter. This improves both fertility and drainage, creating the loamy texture the plant prefers. Maintaining a soil pH between 6.5 and 7.5 provides the ideal environment for healthy growth.
Sowing the Seeds
Coriander seeds are small, round, husked fruits, typically containing two seeds within each casing. To improve germination rates, lightly crush the husks before planting to help split the fruit and allow water to reach the seeds. Soaking the seeds overnight can also soften the outer layer, speeding up the germination process, which can otherwise take up to three weeks.
Sow the seeds directly into the prepared garden bed, as coriander has a long taproot and responds poorly to transplanting. Plant the seeds shallowly, covering them with only one-quarter to one-half inch of soil. For leaf harvest, thin the seedlings to stand about two inches apart. If the goal is seed production, use a wider spacing of six to ten inches for larger, bushier plants.
To ensure a continuous supply of cilantro leaves, practice succession planting by sowing a small batch of seeds every two to three weeks. This technique accounts for the plant’s tendency to “bolt,” or go to seed, quickly as the season warms, maintaining a fresh supply of new plants throughout the cooler parts of the growing season.
Essential Post-Planting Care
Consistent moisture is important for young coriander plants, but the soil must never become waterlogged. Keep the soil evenly moist until the seeds germinate, and continue regular watering to prevent stress that can trigger premature bolting. Once the seedlings are a few inches tall, thin them to the desired spacing to promote good airflow and reduce competition.
The primary challenge is managing bolting, the plant’s natural response to stress, primarily high heat and long daylight hours. Once temperatures consistently climb above 75°F, the plant rapidly sends up a tall flower stalk, and the leaves become lacy and less flavorful. Providing afternoon shade and ensuring steady water are the most effective ways to delay this process.
Coriander does not require heavy feeding; too much nitrogen fertilizer can encourage rapid, leggy growth and earlier bolting. If the soil was properly amended with compost before planting, additional fertilizer is usually unnecessary. If plants show signs of nutrient deficiency, apply a light, balanced liquid feed sparingly.
Harvesting Coriander
Leaf harvest, or cilantro, can begin when the plants are about six inches tall, typically less than a month after sowing. To maximize leaf production, harvest the outer leaves and stems first, trimming them close to the ground while leaving the central growth point intact. Frequent harvesting encourages the plant to produce more foliage and helps delay flowering.
If the goal is to harvest coriander seeds, allow the plant to fully mature and bolt, resulting in small white flowers. Once the flowers fade, the plant produces small, round seed heads. Wait until the entire plant begins to turn brown and the seed heads are completely dry and light brown.
To collect the seeds, cut the stalks and place the heads in a paper bag, hanging it upside down in a cool, dry place. As moisture evaporates, the seeds will naturally fall into the bottom of the bag. Collect the seeds, store them in an airtight container, and use them whole or crushed for cooking.