Basil microgreens are the young seedlings of the common basil plant, harvested shortly after the first set of leaves appears. These young plants offer a more concentrated flavor profile than their mature counterparts, delivering sweet, anise-like spice. Growing these greens indoors is a quick process, often yielding a harvest in just two to three weeks. This guide focuses on the techniques required to successfully cultivate a dense crop of basil microgreens in a controlled indoor environment.
Essential Materials and Tray Setup
Successful indoor cultivation requires selecting the right equipment. Shallow growing trays are used in a two-tray system: one tray has drainage holes and fits inside a solid tray without holes. This arrangement facilitates bottom watering, which keeps the foliage dry and reduces the risk of fungal issues.
The growing medium should be finely textured and sterile, such as coconut coir or a fine-grade organic potting mix. Avoid heavy garden soil, which can compact and harbor pathogens. Basil requires a high density of seeds, so use high-quality, untreated seeds intended for microgreen production. A clear humidity dome or similar cover is needed initially to maintain high moisture levels and encourage germination.
Preparing Basil Seeds and Sowing Density
Preparing basil seeds requires pre-soaking in cool water for four to six hours to break their natural dormancy. This soaking period allows the seed coat to soften and initiate germination quickly and uniformly.
Soaking results in a thick, gelatinous coating, known as mucilage, which surrounds each seed. This sticky substance aids in the adherence of the seeds to the growing medium. After soaking, drain the seeds and spread them densely across the medium surface, aiming for a single, packed layer without overlap.
Once sown, lightly mist the seeds and cover them with the humidity dome or a second tray to initiate the blackout phase. This darkness and humidity creates a warm, moist environment that accelerates germination. Placing a light weight, such as a brick, on the top tray encourages seedlings to develop strong root systems and uniform height as they push against the resistance.
Maintaining Growth: Lighting, Watering, and Airflow
The blackout phase typically lasts for three to five days, or until the first white root hairs are visible and the seedlings begin to lift the cover. At this point, the cover and any weight must be removed, and the tray should be immediately placed under a source of supplemental light. Full-spectrum LED or fluorescent shop lights provide the light wavelengths necessary for photosynthesis and healthy green color development.
The light source should be positioned close to the seedlings, typically 6 to 12 inches above the tray, and maintained for 10 to 16 hours per day. Keeping the light close prevents the seedlings from stretching too quickly, a common issue known as etiolation, which results in weak, pale stems. Maintaining the ambient temperature in the growing area between 70 and 75 degrees Fahrenheit supports vigorous growth.
Watering must be performed from the bottom by pouring water into the solid tray below the drainage tray, allowing the medium to wick up moisture. This method ensures that the foliage remains dry, which helps prevent common fungal diseases like damping off and mold growth. Consistent air circulation is necessary; using a small oscillating fan directed away from the tray helps to gently move the air, strengthening the stems and reducing surface moisture.
Timing the Harvest and Post-Harvest Storage
The best time to harvest is between 14 and 21 days after sowing, when the cotyledons are fully open. Harvest should occur just as the first set of true leaves begins to emerge, but before they fully dominate the plant structure.
To harvest, use clean, sharp scissors or a knife to cut the stems just above the soil line. Ensure no soil or growing medium is collected, as cutting too low introduces soil particles. Basil plants do not typically produce a second harvest, so the growing medium and remaining roots are usually discarded after the initial cut.
After harvesting, gently clean the microgreens by briefly rinsing them or patting them with a damp paper towel to remove debris. For storage, place the greens in an airtight container lined with a dry paper towel to absorb excess moisture. Stored this way in the refrigerator, basil microgreens remain fresh for up to one week.