What we traditionally know as spring onions are technically green onions or scallions (Allium fistulosum) – they do not form a bulb and instead have stiff white stalks with stringy roots. True spring onions, or salad onions, are an immature onion (Allium cepa); they form a small, rounded bulb and are harvested in spring or early summer. Regardless of the species, both are easy to grow and versatile kitchen ingredients.
What you need to know about spring onions
Name: spring onion, scallion, shallots, eschalots, green onion, Allium fistulosum.
Height: 30–50cm.
Plant type: perennial bunching onion also grown as an annual.
Foliage: long, slender and hollow.
Climate: all climates.
Soil: moist, slightly acidic (pH 5–6), well-drained.
Position: full sun, protect from strong winds.
Flowering and fruiting: globular heads of small, white flowers. Seed pods are pale green to white and age to pale grey and eventually open to release a small black seed.
Feeding: not required.
Watering: water regularly.
Appearance and characteristics of of spring onions
Spring onions or green onions have long, slender green leaves that can grow up to 50cm tall. The leaves are hollow and have a mild onion flavour when crushed. Just below the ground hides the stiff white stalks or shanks – they do not form or develop bulbs. The whole plant can be harvested after eight weeks, or the leaves can be cut earlier for use.
How to use spring onion
The leaves can be cut regularly and used to impart a mild onion flavour. Use it to garnish salads, vegetables, meats, fish or other dishes. They can also be cooked in stir fries or grilled for a side dish.
The white spring onion stalks have a more intense onion flavour and are ideal cooked, especially in dishes that have a long cooking time, for example stews or soups. It can also be eaten raw if you like the pungent taste.
How to grow spring onions
Spring onions can be grown easily from seed or seedlings. They will grow all year round in tropical and sub-tropical climates, but are better suited to spring to autumn in warm and cool temperate zones. To grow through the winter in temperate zones, plant in pots so they can be easily moved inside or into a protected spot when frost is expected.
Spring onions prefer a sunny spot with moist, well-drained soil. They like the soil to be slightly acidic (pH 5–6) but aren’t too fussy and can grow in soils up to pH 7. Check your soil pH and use a soil acidifier to lower the pH if needed. Additionally, improve the soil with compost or well-rotted manure. In pots or troughs, use a good quality potting mix.
Create shallow furrows, sow seeds and lightly cover. Water with a light shower to avoid dislodging the seeds. If raising seeds in trays, transplant when leaves are approximately 15cm tall. They will be ready to harvest in eight weeks.
Sow successive crops every 3–4 weeks to prolong the harvest.
Caring for spring onions
Spring onions are easy going but like to be watered and fed regularly. In hot weather, cover with a shade cloth to provide protection from the afternoon sun. The heat can cause the tender leaves to wilt and burn. A layer of organic mulch will also help keep the soil cool and reduce water loss.
How often should you water and feed spring onions?
Water regularly to keep the soil moist. Fertiliser is generally not required as it draws on the nutrients added during soil preparation.
Diseases and pests that affect spring onion
Aphids are the most common pest of spring onions. They’re small and can sometimes be difficult to spot as they camouflage so well with the foliage. Treat with a soap-based spray like Natrasoap. Downy mildew can sometimes be a problem, especially in humid conditions. Ensure plants are well spaced to allow air circulation and treat with a fungicide if needed.
How and when to harvest spring onions
Snip leaves as needed for cooking. Otherwise the whole plant can be harvested eight weeks from sow date.
Safety tip
After applying fertiliser, delay harvesting for a few days and rinse well before cooking and eating. If using products to deal with pests, diseases or weeds, always read the label, follow the instructions carefully and wear suitable protective equipment. Store all garden chemicals out of the reach of children and pets.
If you like this then try
Garlic chives: grow clumps of this perennial herb for a wonderful, mild garlic flavour.
Radish: a fast-growing vegie that adds the perfect crunch to salads.
Rocket: a quick-growing leafy green that packs a peppery punch.
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