How to Grow Spring Onions
Allium fistulosum
Spring onions (scallions) are a quick, easy crop for full sun and free-draining soil. Direct sow thinly in shallow drills from spring through late summer; succession sow for continuity. Keep the seedbed evenly moist for steady growth and mild flavour. Thin lightly for straight stems or grow in clumps for bunching. Protect early sowings with fleece in cold snaps. Harvest at pencil thickness or younger; use fresh for best crunch.
When to Start
Direct sow outdoors as soon as soil reaches 5°C — typically early to mid spring. Can also be started indoors 4 weeks earlier for a head start.
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Growth Stages
Approximate days from start
Care Essentials
- Light balanced feed at sowing. Quick-growing — rarely needs much feeding.
- Sow every 3–4 weeks for continuous supply. Quick and easy — ready in 8–12 weeks.
Growing Conditions
- Min. soil temperature
- 5°C+
- Germination temperature
- 10–25°C
Pet Safety
- Sow indoors
- —
- Transplant out
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- First harvest
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Spacing & Planting
| Plant spacing | 2 cm |
| Row spacing | 15 cm |
| Sow depth | 1 cm |
| Mature height | 30 cm |
| Mature spread | 5 cm |
Also known as Scallions or Bunching Onions. Sown thickly in a band to be harvested before they bulb up.
Pests & Diseases
Pest Onion Fly
Identification: Plants wilt and yellow despite adequate water; small white maggots found at the base of stems when pulled; soft, rotting tissue
- Cover rows with fine mesh or enviromesh from sowing to prevent egg-laying
- Firm soil around plants — loose soil attracts egg-laying females
- Rotate allium crops on a 3-year cycle
- No effective chemical treatments available to home gardeners; barrier methods are the primary control
Pest Allium Leaf Miner
Identification: Lines of white dots on leaves where adult flies have punctured tissue; brown pupae visible inside leaves; distorted, twisted growth
- Cover crops with fine mesh from March to April and again September to November
- Check plants regularly and remove any with visible mines or pupae
- Rotate allium crops
- No effective chemical treatments; physical barriers are the only reliable control
Pest Onion Thrips
Identification: Silvery-white streaks and patches on leaves; tiny, slender yellow-brown insects visible on foliage; leaves may become distorted
- Spray with insecticidal soap
- Keep plants well-watered as thrips prefer dry conditions
- Encourage natural predators
- Spray with a contact insecticide containing pyrethrins
Disease Downy Mildew Peronospora destructor
Symptoms: Pale, greyish-purple fuzzy growth on leaves; leaves yellow from the tips downwards and collapse; plants may die in severe cases
Treatment: Remove affected foliage; improve air circulation; avoid overhead watering
Prevention: Space plants well; ensure good airflow; avoid wet foliage; plant in well-drained soil; rotate crops
Disease Rust Puccinia allii
Symptoms: Bright orange pustules on leaves; leaves yellow and die back prematurely; reduced plant vigour
Treatment: Remove badly affected leaves; improve air circulation
Prevention: Space plants well; avoid high-nitrogen feeds; rotate allium crops; clear debris at end of season
Disease White Rot Sclerotium cepivorum
Symptoms: Yellowing and wilting foliage; fluffy white fungal growth at the base of plants; small black sclerotia visible in the mycelium
Treatment: No cure — remove and destroy infected plants and surrounding soil; do not compost
Prevention: Never plant alliums in soil where white rot has occurred; rotate on a very long cycle (8+ years); avoid moving contaminated soil
Growing Conditions
| Min. soil temperature | 5°C |
| Germination temperature | 10–25°C |
| Base growth temperature | 5°C |
| Min. daylength to start | 8.5h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Spring Onions?
- Plant Spring Onions 2cm apart with 15cm between rows.
- When can I harvest Spring Onions?
- Spring Onions is ready to harvest approximately 45 days after transplanting.
- Is Spring Onions frost hardy?
- Spring Onions is classified as Hardy.
