Onion Seeds UK: A Guide to Growing Onions from Seeds

Onions are a staple in British kitchens, valued for their flavor, versatility, and nutritional benefits. Growing onions from seeds in the UK is a rewarding process that allows gardeners to enjoy fresh, homegrown produce. Onion seeds are widely available in the UK, offering a variety of options, from red onions to white and golden varieties, each suited to different culinary uses.

This guide provides everything you need to know about onion seeds in the UK, including where to buy them, how to grow onions from seeds, and tips for a successful harvest.

Why Grow Onions from Seeds?

1. Cost-Effective

• Growing onions from seeds is more economical compared to buying onion sets or transplants.

2. Greater Variety

• Onion seeds offer a wider range of options, including unique varieties not commonly available as sets.

3. Healthier Plants

• Onions grown from seeds are less prone to disease, ensuring a healthier crop.

Popular Onion Seed Varieties in the UK

1. Red Baron:
   • A popular red onion variety with a sweet flavor and vibrant color, ideal for salads.
2. Sturon:
   • A classic golden onion known for its long storage life and reliable yields.
3. Ailsa Craig:
   • A large, sweet white onion perfect for cooking.
4. Bedfordshire Champion:
   • A traditional UK variety known for its strong flavor and excellent storage.
5. Spring Onions (White Lisbon):
   • Quick-growing green onions that can be harvested young for salads and garnishes.

Where to Buy Onion Seeds in the UK

1. Garden Centres

• Most garden centres across the UK stock a variety of onion seeds suitable for local growing conditions.

2. Online Retailers

• Websites like Thompson & Morgan, Suttons Seeds, and Marshalls offer a wide selection of onion seeds with detailed planting instructions.

3. Local Allotment Stores

• Many allotment associations sell seeds that are well-suited to the local climate and soil.

How to Grow Onions from Seeds in the UK

1. Best Time to Sow Onion Seeds

• Indoors: Late winter (January–February) to give the seeds a head start.
• Outdoors: Early spring (March–April), once the risk of frost has passed.

2. Preparing the Seeds

• Soak the seeds in water overnight to promote faster germination.

3. Sowing Onion Seeds Indoors

1. Use seed trays or pots filled with fine seed compost.
2. Sow the seeds thinly and cover with a light layer of compost.
3. Place the trays in a warm location (15–20°C) with good light.
4. Water gently to keep the compost moist but not waterlogged.

4. Transplanting to the Garden

1. Harden off seedlings by gradually exposing them to outdoor conditions over 7–10 days.
2. Transplant to a well-drained, sunny spot in the garden with fertile soil.
3. Space seedlings 10–15 cm apart in rows 30 cm apart.

5. Direct Sowing Outdoors

1. Prepare the soil by adding compost or well-rotted manure.
2. Sow seeds thinly in shallow drills (1 cm deep) and cover with fine soil.
3. Thin seedlings to the correct spacing as they grow.

Onion Care and Maintenance

1. Watering

• Onions need consistent moisture, especially during dry spells. Avoid overwatering to prevent rot.

2. Feeding

• Apply a balanced fertilizer every few weeks to promote healthy growth.

3. Weeding

• Keep onion beds free from weeds, which compete for nutrients and space.

4. Pests and Diseases

• Common Pests: Onion fly and thrips.
• Diseases: Downy mildew and white rot.
• Use netting to protect young plants and practice crop rotation to minimize disease risks.

Harvesting and Storing Onions

1. Harvesting

• Onions are ready to harvest when the leaves turn yellow and start to fall over.
• Gently lift the bulbs using a garden fork and leave them to dry in a sunny, well-ventilated spot.

2. Storing

• Once the onions are fully dried, remove excess soil and trim the tops.
• Store in a cool, dry place in mesh bags or trays for several months.

Tips for Successful Onion Growing

1. Choose the right variety for your culinary needs and growing conditions.
2. Start seeds indoors for an early harvest and better success rates.
3. Use crop rotation to prevent soil-borne diseases.
4. Protect young plants from frost and pests with cloches or netting.

Top 10 Questions About Onion Seeds in the UK

1. When is the best time to sow onion seeds in the UK?

Late winter (indoors) or early spring (outdoors), depending on your local climate.

2. What are the advantages of growing onions from seeds?

Cost-effectiveness, greater variety, and healthier plants compared to onion sets.

3. What are the most popular onion seed varieties in the UK?

Popular varieties include Red Baron, Sturon, Ailsa Craig, and Bedfordshire Champion.

4. How long does it take for onions to grow from seeds?

Onions typically take 6–7 months from seed to harvest.

5. Can I grow onions indoors?

Yes, start seeds indoors in late winter and transplant them outdoors when conditions improve.

6. Do onions need full sun to grow?

Yes, onions thrive in sunny, well-drained locations.

7. How do I prevent pests and diseases in onions?

Use netting, practice crop rotation, and keep the growing area weed-free.

8. Can onion seeds be planted directly in the garden?

Yes, sow seeds directly in the garden in early spring after the risk of frost has passed.

9. How should I store harvested onions?

Dry onions thoroughly, then store in a cool, dry place with good ventilation.

10. Where can I buy onion seeds in the UK?

Buy onion seeds from garden centres, online retailers, or local allotment stores.

Conclusion

Growing onions from seeds in the UK is a rewarding process that provides fresh, flavorful, and versatile produce for your kitchen. With a wide range of varieties available, gardeners can enjoy experimenting with different types of onions, from sweet red to robust white varieties. By following the right planting and care techniques, you can ensure a successful onion harvest and enjoy the satisfaction of homegrown produce.