Spring onions

Introduction

Spring onions (also called salad onions, green onions, or scallions) are a fast, versatile crop. They’re ideal for small gardens, containers, or filling gaps between slower vegetables, and they can be sown repeatedly for a near-continuous harvest.

Types and Timing

• Varieties: Choose bolt-resistant cultivars such as White Lisbon or overwintering varieties like Performer for year-round sowing.

• Sowing window (UK):

  • Outdoors: March–September (succession sow every 2–3 weeks).

  • Overwintering types: Sow August–October for spring harvests.

• Harvest: Usually 8–12 weeks after sowing.

Site and Soil Requirements

• Light: Full sun is best, though they’ll tolerate partial shade.

• Soil: Well-drained, fertile soil with a fine tilth. They don’t need heavy manuring but benefit from soil enriched with compost the previous season.

• pH: Neutral (6.5–7).

• Containers: Grow well in pots or troughs at least 15 cm deep, using peat-free multi-purpose compost.

Propagation & Planting

• Direct sowing: Sow seeds thinly, 1 cm deep, in drills 15–30 cm apart. Thin seedlings to 2–4 cm spacing.

• Succession sowing: Repeat every few weeks for a continuous supply.

• Module sowing: Alternatively, sow a pinch of seeds in modules and transplant clumps into the garden or containers.

Growing & Maintenance

• Watering: Keep soil consistently moist; dry conditions make bulbs tough and prone to bolting.

• Feeding: Usually not needed if soil is fertile. In containers, use a liquid seaweed feed every few weeks.

• Weeding: Keep beds weed-free to reduce competition.

• Protection: Cover early sowings with fleece or cloches to speed germination and protect from pests.

Harvest and Post-Harvest

• When to harvest: Pull when plants are pencil-thick (usually 8–12 weeks).

• How: Harvest gradually as needed by pulling whole plants or cutting leaves for repeat growth in some varieties.

• Storage: Best eaten fresh. Will keep a few days in the fridge, but flavour and texture deteriorate quickly.

Troubleshooting & Pests

• Onion fly: Can attack; fleece protection helps.

• Rust & mildew: Rare but possible in damp summers. Ensure good airflow and avoid overwatering foliage.

• Bolting: Heat or stress may cause premature flowering - choose bolt-resistant varieties for summer sowing.

Tips from Growers / FAQs

• Succession sowing is the key to a steady supply.

• Great for intercropping - sow between slower crops like carrots, beetroot, or lettuce.

• Ideal for containers on patios or balconies.

Resources & References

• RHS – Grow Spring Onions

• BBC Gardeners’ World – How to Grow Spring Onions

• GrowVeg – Spring Onions Guide