The spring onion, often referred to as a scallion or green onion, is a popular crop for home cultivation. These plants are appreciated for their mild, slightly pungent flavor in both the white base and the green tops, which can be eaten raw or cooked. Their relatively quick maturation time makes them particularly appealing for gardeners seeking a rapid harvest. This guide provides practical steps for successfully cultivating these members of the Allium family from planting to harvest.
Getting Started: Sowing and Planting Methods
Starting spring onions from seed is the most common and economical method, allowing for a continuous supply throughout the growing season. Seeds should be sown directly into the prepared soil approximately 0.5 to 1.5 centimeters deep, ensuring the soil is raked to a fine texture beforehand. For successful growth, space the rows about 15 centimeters apart to allow enough room for maintenance and air circulation.
Gardeners can choose to sow seeds thinly, which minimizes the need for extensive thinning later, or sow them thickly and harvest the thinnings as baby greens. To ensure a steady, uninterrupted harvest, a technique called staggered planting is effective. This involves sowing a new, small batch of seeds every three to four weeks from early spring into late summer.
Another method involves utilizing the rooted white ends of store-bought spring onions, which can be replanted in soil. While these scraps will regenerate new green shoots quickly, they may not offer the same robust growth as plants started from quality seed or small bulbs known as sets. Sets are miniature bulbs that, when planted just below the soil surface, offer a faster path to harvest than seeds, often maturing in about four to five weeks.
Essential Growing Conditions
Spring onions thrive when situated in a location that receives full sun, meaning at least six hours of direct sunlight per day. While they can tolerate slightly less light, aiming for eight to ten hours will promote the most vigorous growth. A sheltered position is beneficial, as the long, hollow leaves can be damaged by strong winds.
The ideal soil for this crop must be loose, fertile, and very well-drained, as the plants are susceptible to rot in waterlogged conditions. Before planting, incorporating well-rotted manure or compost improves the soil structure and adds necessary organic matter. Spring onions generally prefer a soil pH that is slightly acidic to neutral, typically ranging between 5.0 and 7.0.
Consistent moisture is necessary throughout the growth cycle to encourage rapid development and prevent the leaves from becoming tough. The soil should be kept moist but never saturated, which can be managed by watering gently and regularly, especially during dry periods. Due to their shallow root systems, they require careful attention to surface moisture levels.
Ongoing Plant Maintenance
Once the seedlings emerge, managing their spacing is an important step for proper development. If the seeds were sown densely, thinning should occur when the seedlings are still small, ideally spacing the remaining plants about 2.5 to 5 centimeters apart. This practice ensures that each plant has sufficient light, nutrients, and air circulation to develop a healthy stem and root system.
Spring onions are sensitive to competition, so diligent weed control is necessary to prevent stunting their growth. Hand-weeding is the preferred method to avoid damaging the shallow roots of the developing onions. Applying a light layer of organic mulch around the rows can help suppress weed growth while simultaneously helping the soil retain moisture.
Fertilization is often minimal if the soil was prepared with organic matter, but a liquid feed can boost leaf production. Applying a diluted seaweed solution or a balanced liquid vegetable fertilizer two or three times during the growing season can support the production of healthy green leaves. Gardeners should avoid excessive nitrogen, which can make the plants more susceptible to certain diseases.
Monitoring for pests like onion thrips, aphids, and cutworms is advised, especially in warm, dry weather. These pests can be managed by maintaining vigorous plant health and regular inspection. Good air flow, achieved through proper spacing, also helps prevent fungal issues such as downy mildew.
Harvesting and Replanting Techniques
Spring onions are typically ready for harvest around six to eight weeks after sowing, when the stems have reached a usable size but the bulb remains small, generally less than 2.5 centimeters across. There are two main approaches to harvesting, depending on whether the gardener wishes to pull the entire plant or allow it to regrow.
The simplest method is to pull the entire plant from the soil, which is best done when the soil is slightly moist to ease removal and prevent stem breakage. For a continuous yield from a single planting, the “cut and come again” method is effective. This technique involves using a sharp knife or scissors to snip the green leaves about 2.5 to 3 centimeters above the white base, leaving the root plate intact in the soil.
New shoots will regenerate from the remaining base, allowing for multiple harvests from the same plant over time. Spring onions are best used immediately for the freshest flavor, but for short-term storage, they can be placed in the refrigerator, wrapped in a damp paper towel and sealed in a plastic bag, where they will remain fresh for up to two weeks.