Green onions, often called scallions or bunching onions, are a versatile member of the Allium family that can be cultivated year-round in many climates. Growing them from seed offers a distinct advantage over buying sets or transplants, primarily by providing access to a wider selection of varieties tailored to specific tastes or climates. Starting from seed is also highly cost-effective, yielding a plentiful supply of fresh greens from a minimal initial investment. Cultivating these plants successfully begins with understanding their environmental needs and following a structured approach from sowing to harvest.
Preparing for Sowing
The timing for planting green onion seeds depends on your climate and whether you plan to start them indoors or sow them directly into the garden bed. For an early harvest, seeds should be started indoors approximately eight to ten weeks before the last expected frost date in your area. Direct sowing outdoors can begin as soon as the soil is workable and has reached a minimum temperature of about 50°F.
Green onions thrive best when they receive at least six to eight hours of direct sunlight daily, though they can tolerate some afternoon shade, especially in warmer regions. The soil composition is equally important, requiring a fertile, well-draining medium such as a sandy loam to prevent root rot. Ideally, the soil pH should fall within a slightly acidic to neutral range of 6.0 to 7.0 for optimal nutrient uptake. If starting indoors, choose containers that are at least six inches deep to accommodate the initial root growth and ensure they have adequate drainage holes.
Step-by-Step Seed Sowing
When planting green onion seeds, precision in depth and spacing is necessary to encourage healthy, upright growth. Whether sowing indoors or directly outside, the tiny seeds should be planted very shallowly, typically between one-quarter and one-half inch deep. You can plant them in a trench or wide row, spacing the seeds about one inch apart, or sow them in small clusters of four to eight seeds each to help the delicate seedlings support one another as they emerge.
After the seeds are placed, lightly cover them with soil or potting mix and gently pat the surface to ensure good seed-to-soil contact. Immediately after sowing, the planting area must be watered with a gentle mist or fine spray to prevent the tiny seeds from being displaced or washed away. Maintaining consistent moisture is a requirement during the germination phase, which can take up to ten days, as the seeds must remain continually moist to successfully emerge. Once the seedlings appear, they will have delicate, threadlike sprouts that should be handled with care if transplanting is required.
Essential Care and Maintenance
Consistent moisture management is a continuing necessity throughout the green onion’s growth cycle due to their shallow root structure. The soil surface should be kept evenly moist but never waterlogged, which could lead to fungal diseases and root rot. If the planting area does not receive about one inch of rainfall per week, supplemental watering is recommended, especially in sandy soil which dries out quickly.
Once the seedlings have reached a few inches in height, thinning may be necessary if they were sown too densely to maximize the final yield. Thinning involves removing weaker plants to leave the remaining ones spaced about one to two inches apart, allowing for better air circulation and growth. Green onions generally have minimal fertilization needs, especially if the soil was amended with organic matter before planting. However, a light application of a nitrogen-rich fertilizer can be applied mid-season to support the growth of the green tops. If the seeds were started indoors, the young plants should be transplanted outdoors two to four weeks before the last frost, taking care not to damage the fragile root systems.
Harvesting Your Green Onions
Green onions are ready for harvest when the stalks reach the diameter of a pencil, typically 60 to 80 days from transplanting or 90 to 120 days from seed. The most efficient method for a continuous supply is the “cut and come again” technique. Snip the green tops about one to two inches above the soil line using clean scissors or a sharp knife.
Leaving the white bulb and root plate intact allows the plant to regenerate new green shoots, providing multiple harvests from the same plant. Alternatively, you can pull the whole onion from the soil if the entire plant, including the white base, is required. Pulling the entire plant is often done at the end of the growing season or when the plant begins to bolt. Bolting is indicated by a central stalk forming a bud, which signals the end of the best edible quality.