🧅🌱 Planting Onions UK | How to Grow Your Own Onions from Sets or Seed

🌿 Introduction: Why Grow Your Own Onions?

Onions are one of the easiest and most rewarding vegetables to grow in the UK. They take up little space, store well, and are used in countless recipes.

By growing your own onions, you get:
✔ fresher flavour
✔ better storage quality
✔ a wide choice of varieties
✔ great value for money

Whether you choose onion sets or seed, both methods can produce excellent results when grown correctly.

Below

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🧅📅 1. When to Plant Onions in the UK

Timing depends on whether you’re planting sets or seeds.

Onion sets:

✔ Spring planting: March–April
✔ Autumn planting: October–November (overwintering varieties only)

Onion seeds:

✔ Sow indoors: January–February
✔ Sow outdoors: March–April

Avoid planting into frozen or waterlogged soil.

🌱🪴 2. Growing Onions from Sets

Onion sets are small, immature bulbs and are the easiest option for beginners.

How to plant sets:

✔ choose firm, healthy sets
✔ plant with the pointed end up
✔ leave the tip just above soil level
✔ space 10–15cm apart
✔ rows 25–30cm apart

Water well after planting and keep weed-free.

🌾🌱 3. Growing Onions from Seed

Growing from seed gives more variety and often better storage onions.

How to grow from seed:

✔ sow thinly in modules or seed trays
✔ cover lightly with compost
✔ keep moist and warm
✔ transplant when pencil-thick

Thin seedlings to avoid overcrowding.

☀️🌧️ 4. Best Soil and Position for Onions

Onions thrive in:
✔ full sun
✔ free-draining soil
✔ fertile but not freshly manured ground

Heavy soil should be improved with compost or grit.

💧🌿 5. Watering and Feeding Onions

Onions don’t like extremes.

Watering:

✔ water regularly in dry spells
✔ avoid waterlogging

Feeding:

✔ apply a balanced feed in early growth
✔ stop feeding once bulbs start swelling

Too much nitrogen causes leafy growth instead of bulbs.

🚫❌ 6. Common Onion Growing Problems

Bolting (flowering early)

✔ caused by cold stress or damaged sets
✔ use bolt-resistant varieties

Onion fly

✔ cover crops with mesh
✔ rotate crops yearly

Small bulbs

✔ overcrowding
✔ poor feeding
✔ lack of sunlight

Good spacing is essential.

🌾✂️ 7. Harvesting Onions

Onions are ready when:
✔ foliage turns yellow
✔ tops fall over naturally

Lift gently and allow to dry on the soil surface or under cover for 2–3 weeks.

🏡🧅 8. Storing Onions

Correct storage extends shelf life.

Storage tips:

✔ ensure onions are fully dry
✔ store in a cool, dry, airy place
✔ hang in nets or plaits

Properly stored onions can last 6–9 months.

🌟 FAQs

Are onion sets better than seeds?

Sets are easier; seeds offer more choice and better storage.

Can I plant onions in autumn in the UK?

Yes — use overwintering varieties only.

Why are my onions going to seed?

Cold weather or stressed plants cause bolting.

Do onions need lots of water?

Moderate watering is best — avoid extremes.

How many onions do you get from one set?

One set produces one onion.