Alfalfa sprouts are the tender, mild-flavored seedlings of the alfalfa plant, popular additions to sandwiches and salads. While many people use the common jar method, growing sprouts directly in soil allows them to develop a true root system and a more structured form. This technique requires a specific approach to setup and maintenance for a successful, edible harvest.
Essential Supplies and Soil Preparation
The soil-based method requires a few specific items, starting with shallow trays or containers that are no more than two inches deep. These containers should have drainage holes to prevent waterlogging, which is a common cause of mold development in sprouts. You will also need quality organic potting mix and certified organic alfalfa sprouting seeds.
Begin by filling the chosen container with the potting mix, creating a layer about one inch thick. The soil should be leveled and lightly firmed down, but not compacted, to allow for easy root penetration. Before sowing the seeds, the soil needs to be adequately moistened; use a spray bottle or gently pour water until the entire medium is damp, like a wrung-out sponge, but stop before any water pools on the surface.
Sowing the Seeds
Distributing the seeds correctly is a crucial step that determines the density and quality of the final sprout mat. After rinsing your alfalfa seeds briefly to remove any dust, measure out enough to create a dense, single layer across the prepared soil surface. This layer should cover nearly all the soil, with the tiny seeds touching but not stacked on top of one another.
A common mistake is under-seeding, which results in a sparse harvest. Once the seeds are scattered, gently press them onto the moist soil with the back of a spoon or a flat piece of cardboard. The goal is to ensure excellent seed-to-soil contact without burying the seeds, as alfalfa is a small seed that does not require deep planting. A light tamping is sufficient, and covering the seeds with soil is generally unnecessary.
Post-Planting Care and Growth
The initial phase of growth focuses on germination, which requires darkness and consistent, high humidity. Immediately after sowing, cover the tray with a plastic dome, a second tray, or plastic wrap to create a mini-greenhouse environment. This cover traps moisture, signaling the seeds to break dormancy and begin sprouting within the first three to five days.
Keep the covered tray in a dark location, such as a cabinet or pantry, where temperatures remain consistently between 65 and 75 degrees Fahrenheit. Once the first sprouts emerge and begin to lift the seed hulls, typically on day three or four, remove the cover. Move the tray into a location with indirect sunlight. This exposure is necessary for the sprouts to develop chlorophyll, turning their delicate leaves green, a process called “greening up.”
Watering must be done carefully to prevent flattening the sprouts or saturating the soil. Use a fine misting bottle to lightly spray the surface once or twice daily, or whenever the soil surface appears dry. The air circulation created by removing the dome, combined with gentle misting, helps prevent mold and mildew that can proliferate in overly damp conditions. The sprouts will grow rapidly, reaching harvest readiness when they are about two to three inches tall.
Harvesting and Storage
The entire process, from sowing to harvest, typically takes between seven and ten days, depending on temperature and environmental conditions. The sprouts are ready when they have fully developed their small, green cotyledon leaves and reached the desired height. Harvesting at this stage ensures maximum flavor and nutritional content.
To harvest, use a clean, sharp pair of scissors to cut the sprouts in dense clumps just above the soil line. This ensures that no soil or potting mix contaminates the edible portion. After cutting, gently rinse the harvested sprouts under cool, running water to remove lingering seed hulls and debris.
Thoroughly dry the sprouts before storing them, as excess moisture drastically reduces their shelf life. Spread the rinsed sprouts on a clean paper towel or use a salad spinner to remove surface water. Once dry, transfer them to an airtight container lined with a dry paper towel and store them in the refrigerator, where they will maintain freshness for five to seven days.