Microgreens, the young edible seedlings of vegetables and herbs, are harvested just after the cotyledon leaves have fully developed, offering concentrated flavor and nutrition. They are typically ready for harvest within one to three weeks of planting, making them a rapid source of fresh produce. Growing microgreens in trays provides a clean, controlled, and space-efficient method for consistent, indoor cultivation. This guide simplifies the process, focusing on techniques for a successful harvest right on your countertop.
Essential Supplies and Setup
A successful microgreen setup requires a two-tray system. One tray needs drainage holes to hold the growing medium and seeds, and the second, solid tray serves as a reservoir for bottom watering. The standard size is often 10×20, but smaller options are available for home use.
Growing mediums include fine-textured organic soil mixes or hydroponic mats made from materials like hemp or coir. Soil offers a traditional approach, while hydroponic mats eliminate mess and reduce the risk of soil-borne pathogens. Use untreated, high-quality seeds specifically intended for microgreen production, as typical garden seeds are often treated with chemicals. Basic equipment also includes a simple light source, such as a fluorescent or LED grow light, and a spray bottle for initial misting.
Seeding and Initial Germination
To prepare the tray, fill the drainage tray with one to two inches of moistened growing medium, then lightly level and tamp the surface. Plant microgreens using over-seeding, which involves densely scattering the seeds across the entire surface of the medium. The goal is to create a thick, uniform layer that covers the medium almost completely without creating deep piles of seeds.
After seeding, gently mist the seeds and the medium until thoroughly damp. The next step is the “blackout” period, where the seeded tray is covered with another solid tray and often weighted down. This darkness encourages the seedlings to stretch vigorously, developing robust root systems and uniform height. This phase typically lasts two to four days, or until the sprouts are visibly pushing against the cover tray.
Environmental Management During Growth
Once the seedlings emerge, move them under a light source to end the blackout period. Light provides the energy for photosynthesis, allowing the pale shoots to quickly turn vibrant green. For optimal development, position the light source very close to the plants, a few inches above the tray canopy, and keep it on for 14 to 18 hours per day.
The preferred method for providing moisture is bottom watering, using the solid reservoir tray. Pouring water into the bottom tray allows the growing medium to wick up moisture through the drainage holes, hydrating the roots without wetting the foliage. This technique prevents high moisture levels on the plant surface, which can lead to fungal issues like damping off disease or mold growth.
Maintaining good air circulation is important for preventing mold and ensuring strong stems. Stagnant, humid air promotes pathogenic growth. Use a small fan to gently move air over the microgreens for several hours daily; this simulates a natural breeze and lowers humidity around the dense crop. Maintaining an even temperature, ideally between 65°F and 75°F, contributes to a stable growing environment.
Harvesting and Storage Techniques
Harvest timing is determined by leaf development, usually occurring 7 to 14 days after seeding. The optimal moment to cut the microgreens is when the cotyledons, or seed leaves, are fully open but before the first true leaves develop. Harvesting at this stage ensures the best flavor, texture, and nutritional concentration.
To harvest, use clean, sharp scissors or a knife to cut the stems just above the soil line. Ensure no growing medium or root material is included with the greens. Cutting too low increases contamination risk, while cutting too high reduces the yield. Handle the harvested microgreens as little as possible to prevent bruising.
To maximize freshness, store the microgreens correctly. Avoid washing the greens until immediately before consumption, as excess moisture drastically reduces shelf life and encourages spoilage. Place dry, freshly harvested microgreens in an airtight container lined with a paper towel and store them in the refrigerator. When kept dry, the greens can maintain quality for up to a week.