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Growing Onions All Year Round: Autumn and Winter Planting Guide

Introduction

Onions are one of the most widely used vegetables in the kitchen, forming the base of countless recipes. For UK gardeners, onions are also one of the easiest crops to grow. With the right approach, you can enjoy a steady supply of onions almost all year round.

By combining autumn planting and winter planting, you can stagger your harvests and keep your garden productive through the colder months. This guide will walk you through everything you need to know about growing onions year-round in the UK, focusing on autumn and winter planting for continuous harvests.

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Why Grow Onions All Year Round?

• Consistent supply: Avoid buying onions at the supermarket.
• Efficient use of space: Keep beds productive in autumn and winter.
• Early harvests: Autumn-planted onions are ready weeks earlier than spring onions.
• Staggered cropping: Planting at different times means harvests spread across summer.
• Beginner-friendly: Onion sets are easy to plant and require little maintenance.

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Understanding Onion Planting Seasons

Spring Onions

• Planted: February–March.
• Harvested: July–August.
• Store: Up to 9 months.

Autumn Onions

• Planted: September–October.
• Harvested: June (the following year).
• Store: Around 3–5 months.

Winter Onions

• Planted: November–December (sometimes into January in mild areas).
• Harvested: July.
• Store: Around 3–5 months.

? By combining these timings, you can keep onions coming from early summer into the following year.

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Best Onion Varieties for Year-Round Growing in the UK

For Autumn Planting

• Radar – Cold-hardy yellow onion, reliable cropper.
• Electric – Red onion with great flavour.
• Shakespeare – Disease-resistant, hardy option.

For Winter Planting

• Senshyu Yellow – Japanese overwintering onion, thrives in UK conditions.
• Shakespeare – Works for both autumn and winter planting.

For Spring Planting (to extend the season)

• Sturon – Classic yellow onion with excellent storage.
• Red Baron – Popular red onion variety.
• Hercules – Strong flavour, high yields.

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Preparing Soil for Autumn and Winter Onions

Onions grow best in fertile, well-drained soil with a pH of 6.5–7.5.

1. Choose a sunny spot – at least 6 hours of sunlight daily.
2. Improve drainage – add grit or plant in raised beds if soil is heavy clay.
3. Add organic matter – dig in well-rotted compost before planting.
4. Avoid fresh manure – it can cause soft growth prone to disease.

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Planting Autumn Onions

When to Plant

• September–October in most parts of the UK.
• Earlier in colder regions, later in milder areas.

How to Plant

1. Rake the soil to a fine tilth.
2. Place sets pointy end up.
3. Plant 2–3cm deep, just under the soil surface.
4. Space 10cm apart, rows 25–30cm apart.
5. Firm gently and water lightly.

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Planting Winter Onions

When to Plant

• November–December, and up to early January in mild climates.

How to Plant

1. Prepare the soil as for autumn onions.
2. Plant sets 2–3cm deep, tip just visible above the soil.
3. Space 10cm apart in rows 25–30cm apart.
4. Protect with fleece in very cold or exposed areas.

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Caring for Autumn and Winter Onions

During Winter

• Growth slows and onions remain mostly dormant.
• Check after frosts — firm down any sets lifted out of the soil.
• Protect from birds with netting (they like to pull up loose sets).

In Spring

• Growth resumes as days lengthen.
• Weed regularly, as onions hate competition.
• Feed with a nitrogen-rich fertiliser (e.g., blood meal or poultry pellets).

In Early Summer

• Water consistently in dry spells.
• Switch to a potassium-rich feed (like tomato fertiliser) to encourage bulb swelling.
• Stop watering when leaves begin to yellow.

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Harvesting Autumn and Winter Onions

Signs Onions Are Ready

• Leaves turn yellow and topple over.
• Bulbs swell and feel firm to the touch.

Harvesting

• Autumn onions: Usually ready in June.
• Winter onions: Usually ready in July.
• Use a fork to lift bulbs gently — don’t pull by hand.

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Curing and Storing Onions

• Cure onions in a dry, airy place for 2–3 weeks.
• Once skins are papery, trim roots and stems.
• Store in mesh bags, nets, or braids.
• Keep in a cool, ventilated space (not in plastic bags).
• Autumn/winter onions store for 3–5 months, while spring onions can last up to 9 months.

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Common Problems with Autumn and Winter Onions

• Birds pulling sets – cover with netting or fleece.
• Rot in wet soils – ensure well-drained soil or raised beds.
• Frost heave – firm sets back into place after hard frosts.
• Overcrowding – leads to small bulbs.
• Bolting – some onions may flower early, especially if stressed. Remove flower stalks to focus energy on bulbs.

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Year-Round Onion Growing Strategy

To enjoy onions almost all year:

1. Plant autumn onions in September–October.
2. Plant winter onions in November–December.
3. Plant spring onions in February–March.
4. Harvest in stages: June (autumn onions), July (winter onions), August (spring onions).
5. Cure and store onions to last into the following year.

This way, you’ll always have homegrown onions available.

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Conclusion

Growing onions year-round is easy once you understand the differences between autumn, winter, and spring planting. Autumn onions establish early, winter onions extend the season, and spring onions provide longer storage. By combining all three, UK gardeners can enjoy a continuous supply of onions with very little effort.

For beginners, autumn and winter onions are the perfect starting point — they require minimal care through the colder months and reward you with early summer harvests. With a little planning, you’ll never be short of onions again.

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Top 10 Questions About Growing Onions Year-Round

1. Can onions really be grown all year round in the UK?
Yes — by planting in autumn, winter, and spring, you can stagger harvests for continuous supply.

2. What’s the difference between autumn and winter onions?
Autumn onions are planted earlier (September–October) and harvest earlier. Winter onions are planted later (November–December) and harvest slightly later.

3. Do onions survive frost?
Yes, overwintering onion varieties are bred to handle UK winters.

4. How deep should I plant onion sets?
2–3cm deep, just under the soil surface.

5. Do onions need much care over winter?
No, they require little maintenance apart from checking for frost heave and bird damage.

6. When are autumn onions ready to harvest?
Usually June.

7. When are winter onions ready to harvest?
Usually July.

8. How long do autumn and winter onions store for?
Typically 3–5 months, shorter than spring onions.

9. Can onions be grown in pots over winter?
Yes, but use deep containers (at least 25cm) with good drainage.

10. What’s the best way to get onions all year round?
Plant autumn onions, winter onions, and spring onions for staggered harvests and continuous supply.

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