🧅🌱 When to Plant Spring Onions in the UK

🧅 Introduction: Spring Onions Are Quick—But Timing Still Matters

Spring onions are one of the fastest and easiest crops to grow in the UK, making them ideal for beginners and succession sowing. While they are forgiving, sowing at the right time ensures steady growth, good flavour, and a long harvesting period. Understanding when to plant spring onions in the UK helps you avoid slow winter growth or bolting in hot weather.

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📅 Best Time to Plant Spring Onions in the UK

Spring onions can be grown for much of the year.

Key planting stages:
✔ Sow seeds: February to September
✔ Transplanting: Not usually required
✔ Harvest: April to November

With regular sowing, spring onions can be harvested almost continuously.

🌱 When to Sow Spring Onion Seeds

✔ sow from February under cover or in mild areas
✔ sow outdoors from March to September
✔ sow little and often for a continuous crop

Early sowings may need protection in colder regions.

🌱 Outdoor Sowing Through the Seasons

Early Spring (February–March)

✔ sow under cover or fleece
✔ slower growth in cool soil

Spring to Summer (April–June)

✔ fastest and most reliable growth
✔ ideal time for regular sowings

Late Summer (July–September)

✔ suitable for autumn harvests
✔ growth slows as days shorten

🌡️ Soil Temperature and Growing Conditions

Spring onions grow best when:

✔ soil temperature is 7–20°C
✔ soil is light, fertile, and free-draining
✔ moisture is consistent

Dry soil can cause thin or tough stems.

🌍 Regional Differences Across the UK

Cold Areas (Scotland, northern England, higher ground)

✔ start sowing from March
✔ use fleece for early crops

Mild Areas (southern England, coastal regions)

✔ sow from February
✔ longer growing and harvesting window

Always adapt to local soil warmth.

🪴 Growing Spring Onions in Containers

✔ ideal for pots, troughs, and raised beds
✔ use containers at least 15–20 cm deep
✔ sow fairly densely

Containers allow easy, frequent sowing close to the kitchen.

❄️ How Spring Onions Handle Cold and Heat

✔ tolerate light frost
✔ cool weather improves flavour
✔ extreme heat can cause bolting

Spring and early summer sowings usually give the best results.

🚫 Common Spring Onion Growing Mistakes

❌ sowing too thickly
❌ letting soil dry out
❌ leaving crops unharvested too long
❌ poor soil fertility

Harvest promptly for tender stems.

🌟 FAQs

What month do you plant spring onions in the UK?

Spring onions are usually sown from February to September.

Can spring onions be grown all year round?

They can be grown most of the year, though winter growth is slow without protection.

How long do spring onions take to grow?

Typically 6–10 weeks, depending on conditions.

Do spring onions need full sun?

Yes, though they tolerate light shade.

Can I sow spring onions in autumn?

Yes, for late autumn harvests, but growth slows as temperatures drop.