Exact sowing dates, succession planting guide, best varieties, and regional timing for spring onions in UK gardens and allotments.
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Sowing dates and growing advice verified against RHS guidance by the SoilCommander Growing Team.
Spring Onion Planting Calendar UK
| Task | Timing | Notes |
|---|---|---|
| Sow under cover | February – March | Modules or trays; 10–15°C minimum |
| Direct sow outdoors | March – July | Every 2–3 weeks for continuous harvest |
| Autumn / overwintering sow | August – September | Use White Lisbon Winter Hardy; harvest March–April |
| Harvest | May – October | 8–12 weeks from sowing; pull when pencil-thick |
Key Tips
- Succession sow every 2–3 weeks from March to July for a continuous supply
- Avoid sowing in soil below 7°C — seeds rot rather than germinate
- Don't miss the August–September overwintering window for March–April harvests
- Pairs well with carrots — onion scent deters carrot fly
Browse all sowing dates in the UK vegetable planting calendar · Explore all UK vegetable growing guides
Relevant next steps
Plan The Timing Before You Sow
Use the planting window with a planner, seed-starting setup, and the full calendar so dates stay practical for your garden.
Plan the next step
Use the printable UK Vegetable Garden Planner to turn this guide into sowing dates, bed layouts, and weekly garden tasks.