How to grow Spring Onion

At a glance

🌱 Grow your Spring Onion with GardenDex

• Reminders to water it, timed to your weather and whether it's in a pot
• Frost and disease alerts for your garden, the night before
• Follow it from seed to harvest, and see what your garden grew in $
• Point your camera at any plant or bug to identify it

🗓️ When to plant

Sow seeds in early spring as soon as soil is workable, or in mid-to-late summer for autumn harvest. In mild climates, sow through autumn and winter for year-round crops.

🌰 How to plant

1. Sow seeds directly outdoors ¼ in (0.6 cm) deep in rows or scattered in prepared beds.
2. Keep soil moist until seedlings emerge (7–10 days).
3. Thin seedlings to desired spacing once they're 5 cm (2 in) tall.
4. For continuous harvests, sow new seeds every 2–3 weeks throughout the growing season.

💧 Care

• Weed regularly and gently to avoid damaging shallow roots.
• Apply a 5 cm (2 in) mulch layer to retain moisture and suppress weeds.
• Feed with balanced, nitrogen-rich fertilizer every 3–4 weeks for lusher green tops.
• Ensure good air circulation to prevent fungal diseases.
• Water at soil level in the morning to keep foliage dry.

🧺 Harvest

Begin harvesting baby onions at 30–40 days by pulling alternate plants to thin the row, or wait 60–80 days for full-sized onions. Harvest outer leaves anytime, or pull entire plants once the white base is pencil-thick.

🐛 Common problems

Onion fly or maggots: Cover young plants with fine netting, remove affected plants immediately, and rotate crops yearly.

Powdery mildew: Improve air circulation, avoid overhead watering, and spray with diluted neem oil if needed.

Rust: Remove infected leaves promptly and ensure plants have adequate spacing and airflow.

🤝 Companion plants

💚 Good neighbours: Carrots, Lettuce, Strawberries, Tomatoes

⚠️ Keep apart from: Beans, Peas

More vegetables guides