Keter Manor Outdoor Apex Double Door Garden Storage Shed (6 x 8ft)
A durable and stylish beige and brown garden storage shed perfect for storing garden tools, equipment, bikes, and outdoor essentials. Weather-resistant, low maintenance, and ideal for any garden or allotment setup.
Vegetable Plants & Seedlings
Browse Plants
All-Purpose Compost & Soil Improvers
View Compost
Plant Feed & Fertiliser for Strong Growth
Shop Fertiliser
❄️🧅🌱 Growing Onions from Seed in January
🌿 Introduction: Why Start Onions from Seed in January?
January is one of the best months to start onions from seed in the UK, especially if you want larger, better-quality bulbs later in the year.
Starting onions early:
✔ gives plants a long growing season
✔ helps produce bigger bulbs than sets
✔ offers more variety choice
✔ reduces the risk of bolting
Although growth is slow at first, onions started in January usually outperform later sowings.
Below
⭐ Check Out Our Recommended Products
• Seed Trays or Modules
Ideal for sowing onions neatly and evenly indoors.
Click here to see them
• Fine Seed Compost
Helps delicate onion roots establish easily.
Click here to see them
• Grow Lights or Bright Windowsill
Prevents weak, leggy seedlings in low winter light.
Click here to see them
🌱🏡 1. Why January Is Ideal for Onion Seed Sowing
Onions need a long growing period to form large bulbs.
By sowing in January:
✔ seedlings establish early
✔ plants grow steadily through spring
✔ bulbs have more time to size up
Slow early growth is normal and beneficial.
🧅🌱 2. Best Onion Varieties to Sow in January
Not all onions perform equally well from early sowings.
Good varieties for January sowing:
✔ ‘Ailsa Craig’
✔ ‘Sturon’
✔ ‘Bedfordshire Champion’
✔ ‘Rijnsburger’ types
Choose varieties suited to UK conditions and long seasons.
🌱🪴 3. How to Sow Onion Seeds in January
Sow onions indoors for best results.
✔ fill trays with fine seed compost
✔ sow seeds thinly on the surface
✔ lightly cover with compost or vermiculite
✔ water gently
Keep compost moist but not wet.
🌡️🌱 4. Germination and Temperature Needs
Onions don’t need high heat.
✔ ideal temperature: 10–15°C
✔ germination usually takes 10–14 days
✔ avoid placing near strong heat sources
Cool, steady conditions produce stronger seedlings.
🌱🛡️ 5. Caring for Onion Seedlings in Winter
Winter care is about balance.
✔ give as much light as possible
✔ rotate trays to prevent leaning
✔ water sparingly
✔ ensure good air circulation
Leggy seedlings mean they need more light.
🌱✂️ 6. Should You Trim Onion Seedlings?
Yes — trimming can help.
✔ trim leaves to about 5–7cm tall
✔ encourages thicker growth
✔ reduces tangling
Use clean scissors and don’t over-trim.
🌱📦 7. Potting On or Growing On in Trays
Onions can be handled in two ways.
✔ grow on in trays until planting out
✔ or gently separate and pot on
Both methods work — minimal disturbance is best.
🌱🌿 8. When to Plant Out Onion Seedlings
Onions are hardy once established.
✔ plant out from March–April
✔ harden off gradually
✔ space plants 10–15cm apart
Early planting helps bulbs develop fully.
⚠️❌ 9. Common Mistakes When Growing Onions from Seed
❌ sowing too thickly
❌ overwatering
❌ not enough light
❌ planting out too late
Most problems come from low light and excess moisture.
🌟 FAQs
Is January too early to sow onions from seed?
No — it’s one of the best times in the UK.
Do onion seedlings need heat?
No — cool conditions are better.
Why are my onion seedlings thin and floppy?
They need more light.
Can beginners grow onions from seed in January?
Yes — onions are beginner-friendly with patience.
Are onions from seed better than sets?
Often yes — they’re less prone to bolting and can grow larger.