Cilantro (Coriandrum sativum) is a versatile herb, prized for its fresh leaves and its seeds, known as coriander. This plant thrives in cool conditions, meaning timing and planting technique are important for a successful harvest. Following specific steps regarding preparation and planting depth ensures seeds sprout and grow into healthy plants.
Preparing the Seeds and Timing
The ideal time to sow cilantro seeds is in the early spring, as soon as the soil becomes workable, or again in the early fall. Cilantro is a cool-season annual that grows best when temperatures are between 50 and 85 degrees Fahrenheit. It will quickly “bolt,” or go to seed, when summer heat arrives, so aim to plant when the soil temperature is consistently between 55 and 70 degrees Fahrenheit.
Cilantro seeds are a small, hard fruit containing two seeds. Gently cracking the outer husk significantly improves germination rates. Crush the fruit lightly to separate it into two halves, allowing water to penetrate. Soaking the seeds for 24 to 48 hours before planting softens the seed coat and encourages quicker sprouting. Allow the seeds to dry slightly after soaking before planting.
Specifics of Seed Depth and Spacing
The required depth for planting cilantro seeds is a shallow one-quarter to one-half inch. This precise depth is important: planting too deeply prevents the seedling from reaching the surface, while planting too shallowly leaves the seed vulnerable to drying out. Using a ruler or a dibber ensures a consistent depth, helping all seeds germinate at a similar rate.
After planting, cover the seeds with soil and gently firm the surface to establish good seed-to-soil contact. This contact allows the seed to draw moisture from the surrounding soil, initiating germination. For growing cilantro primarily for leaves, seeds can be sown close together, about one to two inches apart, allowing for dense planting.
If harvesting for coriander seeds or desiring larger plants, thin the seedlings later to stand six to ten inches apart. For row planting, 12 to 15 inches between rows is recommended to allow for adequate growth and air circulation. This spacing prevents overcrowding, which can encourage the plant to bolt prematurely.
Ensuring Successful Germination
After planting, maintaining constant, gentle moisture in the top layer of soil is crucial for sprouting. The soil must be kept evenly moist but never waterlogged, as excessive water can lead to rot or disease. Consistent moisture breaks the seed’s dormancy, and sprouts should appear within 7 to 21 days, depending on the temperature.
Cilantro seeds do not require light to germinate, but they need warmth. The ideal soil temperature range of 55 to 70 degrees Fahrenheit encourages rapid sprouting. Once seedlings emerge, they prefer full sun exposure, though partial afternoon shade is beneficial in warmer climates to help prevent bolting.
Once the seedlings develop their first true leaves and are a couple of inches tall, thin them to their final spacing to prevent competition for light and nutrients. Overcrowding stresses the plants and triggers bolting, so removing weaker seedlings is necessary. Continued light watering and protection from temperature extremes support the young plants as they establish a healthy root system.