Microgreens are the tiny edible seedlings of various vegetables and herbs, harvested right after the first true leaves emerge. Cilantro microgreens, derived from the Coriandrum sativum seed, offer an intense, fresh citrusy flavor, often more concentrated than the mature herb. Cilantro is a slower-growing microgreen variety that presents challenges due to its hard seed coat and longer germination period. Successfully growing these greens requires specific attention to seed preparation and a controlled initial environment to ensure a high and uniform yield.
Essential Equipment and Seed Preparation
The foundation for a successful crop begins with the right materials, including shallow 10×20-inch growing trays with drainage holes. These trays are paired with solid bottom trays to facilitate bottom watering later in the growth cycle. A fine-textured substrate, such as coconut coir or a premium seed-starting mix, is used as the growing medium. This medium should be leveled and lightly compacted to ensure good water retention, aeration, and a smooth surface for the seeds.
Cilantro seeds are unique compound seeds, naturally containing two embryos encased in a single husk. To accelerate germination and improve consistency, the hard husk must be mechanically cracked or “split” before planting. This can be done by gently crushing the seeds with a rolling pin or by purchasing pre-split seeds, which germinate faster.
Following mechanical preparation, the seeds benefit from a presoak to encourage hydration and break dormancy. Soaking the seeds in clean water for 12 to 24 hours softens the seed coat and quickens the emergence process. This extended soak reduces the overall time needed for germination, which can otherwise be delayed. After soaking, the seeds must be strained and sown immediately to prevent them from drying out.
Sowing Density and the Germination Blackout Phase
Cilantro requires a specific sowing density to prevent overcrowding and potential mold issues. For a standard 10×20-inch tray, the recommended density is 20 to 40 grams of seed, or approximately 7 to 8 seeds per square inch. Since cilantro is grown until the first true leaves appear, it needs slightly more space than faster microgreens harvested at the cotyledon stage. The prepared seeds should be spread uniformly across the pre-moistened growing medium surface without overlapping.
After sowing, the tray enters the germination blackout phase, a period of complete darkness that mimics natural soil cover. This phase is crucial for cilantro, typically lasting 6 to 7 days, which is longer than for many faster-growing microgreens. The darkness encourages etiolation, causing the seedlings to stretch and resulting in taller, more uniform stems as they search for light.
During the blackout phase, the tray should be covered with another tray or dome to block all light. A weight of 5 to 15 pounds is often placed on top, which forces the roots downward to anchor the plant and encourages stronger stems. The ideal temperature for germination is 65°F to 70°F (18°C to 21°C). The tray should be checked periodically to ensure the medium remains moist, often requiring a light misting.
The Growth Cycle: Light, Watering, and Airflow
Once the seedlings have lifted the weight or reached about one inch in height with visible yellow sprouts, they transition out of the blackout phase. Exposure to light immediately halts etiolation and triggers photosynthesis, causing the stems and leaves to turn green. Cilantro microgreens grow best under consistent, high-intensity light for 12 to 16 hours daily. This is typically provided by LED grow lights positioned close to the tray, or by rotating the tray frequently near a bright window.
Proper watering management prevents common issues like damping off or mold, which thrive in high-humidity environments. Once under light, all watering should transition to the bottom-watering method. Water is added directly to the solid tray underneath the growing tray, allowing the medium to absorb it through capillary action. This method keeps the delicate leaves dry and mitigates the risk of fungal growth.
Airflow supports a healthy and disease-free crop, especially once the canopy becomes dense. Using a small fan to gently circulate air above the trays helps reduce humidity and prevents fungal issues. Maintaining this balance of consistent light, dry leaves via bottom watering, and good air movement is necessary for the next two to three weeks of growth.
Harvesting Techniques and Timing
Cilantro microgreens have a longer growth duration, often taking 15 to 25 days from sowing to reach the ideal harvest stage. The optimal time for harvest is determined by the appearance of the first true leaves, which resemble miniature versions of the mature cilantro leaf. Although the initial cotyledon leaves are edible, many growers wait for the true leaves to emerge because they contain the full aromatic profile of mature cilantro.
To prepare for harvest, watering should be stopped 12 to 24 hours in advance to reduce the moisture content of the greens, improving their shelf life after cutting. The greens are harvested using a sharp knife or clean scissors to cut the stems just above the soil line. This ensures no soil particles are collected, as cutting too close can introduce contaminants.
Cilantro will not regrow after harvest because the entire plant is cut above the medium, removing the growth point. The spent medium and root mat should be discarded or composted after the harvest is complete. The freshly cut microgreens should be consumed immediately or stored in a sealed container in the refrigerator.