Spring onions are a popular and easy-to-grow culinary herb, offering a mild onion flavor that enhances a variety of dishes. Their versatility and quick growth cycle make them a favored choice for home gardeners. These plants provide continuous harvests, proving to be a rewarding addition to any garden space.
Understanding the Spring Onion Plant
The spring onion plant (Allium fistulosum) is a perennial vegetable often grown as an annual. It is also known as scallion, green onion, Japanese bunching onion, or Welsh onion, with these terms often used interchangeably. Unlike common bulb onions, spring onions do not form a prominent bulb. Instead, they produce hollow, tubular green leaves and slender white stalks with stringy roots. This distinguishes them from other alliums like chives or leeks.
Planting Spring Onions
Spring onions can be started using several methods. Planting from seed is a common approach; sow seeds directly into well-prepared, moist soil at a depth of 5-6mm (0.2-0.25 inches), spacing them 5mm apart in rows 15cm (6 inches) apart. For continuous harvests, sow new batches every three to four weeks from early spring through autumn. Small bulbs or sets also offer a quicker harvest.
Another effective method involves regrowing spring onions from kitchen scraps. Cut the green tops, leaving 2.5-3 cm (1-1.5 inches) of the white base with roots. Place these root ends in a shallow glass of water, ensuring only the roots are submerged, and position the glass in a well-lit area. New shoots will emerge rapidly. Once new roots and shoots are established, typically after 3-5 days, transplant the regrown sections into soil.
For planting in soil, choose a location that receives full sun, ideally six to eight hours daily. Spring onions thrive in well-drained, humus-rich soil with a pH between 6.0 and 7.0. Incorporating compost or well-rotted manure before planting improves soil structure and nutrient content.
Care and Maintenance for Spring Onions
Consistent moisture is important for healthy spring onion growth, as these plants have shallow root systems. Water regularly, about once a week if there is no rain, ensuring the soil remains moist but not waterlogged to prevent diseases like downy mildew. Container-grown plants may need more frequent watering.
Spring onions are not heavy feeders. A liquid fertilizer can be applied two to three times during their growth, or a balanced fertilizer (such as 10-10-10) every couple of weeks to encourage leafy growth. Fertilization is generally not required if the soil was properly amended with organic matter at planting.
Keep the planting area free of weeds, as they compete for water and nutrients. Common pests include thrips, aphids, and onion maggots. Inspect plants regularly for infestations and consider methods like hosing off aphids or using insect nets. Adequate spacing also helps prevent fungal diseases.
Harvesting Your Spring Onions
Spring onions are typically ready for harvest around eight weeks after sowing, when plants reach about 15-20 cm (6-8 inches) in height and the white bases are still slender. For optimal flavor, harvest them while young. There are two primary harvesting methods: partial harvesting for continuous yield or full harvesting of the entire plant.
To encourage continuous production, snip off green leaves about 2.5-3 cm (1-1.5 inches) above the root line, or leave a small portion of the white stem. This “cut-and-come-again” method allows the plant to regrow new leaves, providing multiple harvests. Spring onions can regrow several times, often four or more flushes of new growth.
If you desire the entire plant, including the white stalk, gently loosen the soil around the plant with a hand fork or trowel and pull it up. To maximize yields, avoid cutting all leaves from a single plant; instead, harvest a few leaves from several plants. If flower stalks appear, snip them off to encourage leaf production.