Green onions (scallions or bunching onions) are cool-weather crops favored for their fast growth and mild flavor, being a non-bulbing member of the Allium family. They are commonly transplanted either by moving seedlings started indoors or by dividing established, overcrowded perennial clumps. Successful transplanting requires aligning the plant’s readiness with optimal environmental conditions.
Identifying the Optimal Time for the Move
The best time for transplanting is determined by the plant’s physical maturity and prevailing weather conditions. Indoor seedlings are ready when they reach six to eight inches in height and have developed at least three true leaves. This usually takes 8 to 10 weeks from initial seeding, resulting in a plant sturdy enough for relocation.
The ideal seasonal window is early spring, as soon as the garden soil becomes workable. Green onions tolerate light frosts, but the soil temperature should be at least 50°F for active root growth. Transplanting must be completed before the intense heat of summer, which can cause the plants to “bolt” or flower prematurely, resulting in tough, less flavorful stalks. For a continuous harvest, a second round of transplanting can be done in late summer or early fall. Established perennial clumps benefit from division and transplanting in the early spring, just as new growth begins, to prevent overcrowding.
Essential Preparation Steps Before Transplanting
Seedlings grown indoors require a gradual adjustment period before being moved permanently outside, a process known as “hardening off.” This step acclimates the plants to harsher outdoor elements like direct sunlight, wind, and fluctuating temperatures. Hardening off should begin about two weeks before the planned transplant date, slowly exposing the seedlings to outdoor conditions for increasing periods each day.
Start by placing the seedlings in a sheltered, shady location for a few hours on the first day, then bring them back inside. Over the next 7 to 14 days, gradually increase their outdoor exposure and the amount of direct sunlight they receive. Concurrently, prepare the garden bed by loosening the soil to a depth of at least six inches and incorporating organic matter, such as compost. Since green onions have shallow roots, rich, well-draining soil is preferred for immediate establishment.
Technique for Successful Transplanting
Before planting, trim both the tops and the roots of the green onion starts, especially if they are leggy or have long roots. Trimming the green tops to about four inches and the roots to half an inch helps reduce transplant shock. This practice encourages the plant to focus its energy on establishing a strong root system rather than supporting an overly large canopy.
The planting process involves creating a narrow furrow or trench about two inches deep in the prepared soil. Space single seedlings or small clusters (four to eight seedlings) roughly one to two inches apart for continuous harvesting. Plant the seedlings slightly deeper than they were growing previously, ensuring the entire white portion of the stem is covered by soil. Immediately after planting and backfilling, water gently and thoroughly to settle the soil around the roots and eliminate air pockets.
Post-Transplant Care for Establishment
The first few weeks following transplant focus on managing soil moisture to promote successful establishment. Green onions have a shallow root system, making them susceptible to drying out quickly after the move. Maintaining consistent moisture is important, but avoid overwatering to prevent root rot.
Monitor the transplanted onions daily for signs of stress, such as wilting or yellowing leaves. If a sudden spike in temperature occurs, providing temporary shade during the hottest part of the day can mitigate stress. Since the plants rely on healthy foliage for growth, a light application of a nitrogen-rich fertilizer can be side-dressed one to two weeks after transplanting to encourage robust green stalk development.