When to sow Spring Onion in the UK
Spring Onion is sown to the calendar rather than to the frost, so the window is much the same wherever you garden in the UK.
Sowing and harvest dates by region
Spring Onion is grown to the calendar rather than to the frost, so the same dates apply across the whole UK and every region below reads the same. Where a plant's timings do follow the frost, Plot shifts them from the Midlands and Lowland Wales baseline using Met Office average frost dates.
| Where you are | Sow indoors | Sow outdoors | Plant out | Harvest |
|---|---|---|---|---|
| South West Coast and Cornwall | early March to late March | early March to late September | early April to late May | early March to late October |
| South Coast and Channel | early March to late March | early March to late September | early April to late May | early March to late October |
| Greater London (Urban Heat Island) | early March to late March | early March to late September | early April to late May | early March to late October |
| South East and Home Counties | early March to late March | early March to late September | early April to late May | early March to late October |
| East Anglia | early March to late March | early March to late September | early April to late May | early March to late October |
| Midlands and Lowland Wales | early March to late March | early March to late September | early April to late May | early March to late October |
| Wales and West Coast | early March to late March | early March to late September | early April to late May | early March to late October |
| Northern England | early March to late March | early March to late September | early April to late May | early March to late October |
| Scotland Lowlands and Central Belt | early March to late March | early March to late September | early April to late May | early March to late October |
| Scotland Highlands and Islands | early March to late March | early March to late September | early April to late May | early March to late October |
| Northern Ireland | early March to late March | early March to late September | early April to late May | early March to late October |
| Channel Islands and Isle of Man | early March to late March | early March to late September | early April to late May | early March to late October |
Growing notes
Sow small batches every couple of weeks from March to September for a continuous supply about two months after each sowing; hardy varieties sown in late summer and early autumn overwinter for a March crop. Ideal for a 30cm pot on a balcony - do not crowd them or downy mildew follows.
At a glance
- Spacing
- 3 cm between plants
- Row spacing
- 20 cm
- Plants per m²
- 150
- Days to maturity
- 60 days
- Yield per plant
- 0.02 kg
- Sun
- Full sun
- Frost tender
- No
- Grows in a container
- Yes, 10 litres or more
- Minimum soil depth
- 15 cm
- Balcony rating
- 5 out of 5
Succession sowing
Worth sowing in batches. Sow again every 14 days, up to about 8 sowings in a season, for a longer picking window rather than one glut.
What usually goes wrong
- onion downy mildew
- onion white rot
- onion fly
- slugs
Companion planting
Grows well near
Keep away from
Related guides
Timings cross-checked against RHS guidance for spring onion.