Kale microgreens are the tiny, edible seedlings of the common kale plant, harvested just after their first pair of leaves, known as cotyledons, fully develop. These immature greens offer a concentrated source of nutrients and a mild, fresh flavor that is less bitter than their mature counterparts. Growing them at home is popular due to their quick turnaround time, typically providing a harvest in less than two weeks. This simple cultivation method allows for a continuous supply of these nutritious greens year-round.
Essential Supplies and Setup
Successful microgreen cultivation begins with gathering the right equipment to create a consistent growing environment. You will need two types of shallow growing trays: one with drainage holes for the growing medium and a second, non-draining tray for bottom watering. For the growing medium, a fine-textured soil mix or a blend of potting soil and coconut coir is recommended to ensure adequate drainage while retaining moisture. When sourcing seeds, select untreated, high-quality kale seeds specifically intended for microgreen or sprouting use.
Kale microgreens require a significant amount of light to photosynthesize and develop their vibrant color, so a dedicated grow light is necessary for optimal results. While a sunny windowsill can work, it often leads to uneven, spindly growth due to insufficient light intensity. Position the light source to be easily adjustable, as the distance between the bulb and the seedlings will change as they grow. Setting up the growing station before sowing ensures a smooth transition once the seeds are ready for light exposure.
Seeding and the Blackout Period
The initial step involves preparing the growing medium by leveling and gently compacting it in the tray to create an even surface approximately one inch deep. Microgreens require a high seeding density; the kale seeds should be spread uniformly and thickly across the entire surface of the soil. Aim for approximately 4 to 5 seeds per square centimeter, a density that nearly covers the soil without excessive overlapping. After sowing, the seeds should be thoroughly misted with a spray bottle to initiate germination without displacing the small seeds.
Immediately following the initial misting, the trays enter the “blackout” period, which encourages strong root development and stem elongation. This is achieved by covering the tray with a second tray or a light-blocking dome, often weighted down. The darkness mimics the environment beneath the soil and forces the seedlings to stretch, making them easier to harvest later. During this phase, which typically lasts 3 to 5 days for kale, the seeds should be checked daily and lightly misted if the surface appears dry.
The weight applied during the initial days helps anchor the emerging roots into the soil and promotes uniform germination. Once the seedlings are about an inch tall and are visually pushing the cover upward, they are ready to be moved into the light. At this point, the plants will appear pale yellow due to the absence of light, a temporary condition known as etiolation, which quickly reverses once photosynthesis begins.
Active Growth and Harvesting Techniques
Once the seedlings are tall enough to stand on their own, the cover is removed, and the tray is transitioned under the grow light. Position the light source a few inches above the tray to provide adequate intensity, typically aiming for 12 to 16 hours of light exposure daily. This exposure triggers the production of chlorophyll, causing the stems and leaves to turn a deep green color. Proper airflow, often maintained by a small fan, is beneficial during this stage to reduce surface humidity and mitigate the risk of mold.
Watering during the active growth phase must shift entirely to the bottom-watering method to keep the delicate foliage dry and prevent fungal issues. This involves pouring water into the solid-bottom tray beneath the growing tray, allowing the soil to soak up moisture through the drainage holes via capillary action. Allow the tray to soak for about 10 to 15 minutes until the top of the soil is moist. Any remaining excess water should then be drained away to prevent the roots from sitting in stagnant water.
Kale microgreens are typically ready for harvest between 8 and 14 days after sowing, once the cotyledons are fully open and developed. This stage offers peak flavor and nutritional density, occurring just before the first set of true leaves begins to emerge. To harvest, use a sharp, clean pair of scissors or a knife to cut the stems in bundles just above the soil line, ensuring no growing medium is included. Microgreens should be consumed immediately for the best taste, but they can be stored in an airtight container in the refrigerator for a few days, provided they are dry when cut.