Allium
How to grow spring onions
Allium cepa / A. fistulosum
Spring onions are the quickest allium, ready eight to ten weeks after sowing, and they fit into any gap in a bed or a pot by the back door. Sow thinly, direct where they are to grow, every three weeks from March to August, and sow a winter-hardy variety in late August or September for pulling in spring. They need no thinning and almost no feeding. Keep the soil moist and pull them young, before the bases swell and the flavour coarsens.
- Hardiness
- Hardy; winter-hardy varieties overwinter
- Position
- Full sun to light shade
- Soil
- Fertile, free-draining
- Ideal pH
- 6.5 to 7.0
- Water
- Moderate, keep moist for mild, tender stems
- Feeding
- Moderate feeder
Sowing and planting spring onions
WhenSow Mar to Aug every 3 weeks (and Sep for spring); harvest 8 to 10 weeks after sowing
Starting off
Direct outdoors from March to August every 3 weeks, germinating in 10 to 14 days at 10 to 20 °C; sow 'White Lisbon Winter Hardy' in September for an April crop. Early sowings go under fleece. Modules with 6 to 8 seeds per cell at 15 °C transplanted as a clump work well in cold springs.
Spacing and planting
Sow 1 cm deep in drills 10 to 15 cm apart and do not thin; aim for seedlings 1 to 2 cm apart, or broadcast in a 10 cm wide band. Ideal for a 20 cm deep pot, trough or windowbox, where a sowing every 3 weeks keeps a continuous supply.
Varieties worth growing
- White Lisbon
- The standard: quick, mild and reliable from spring and summer sowings. If left it forms a small bulb.
- White Lisbon Winter Hardy
- The selection for late August and September sowing; stands the winter and is pulled from March to May.
- Ishikura
- Japanese bunching onion with long, straight white stems that never form a bulb, so it stands for weeks without going over.
- Apache
- Deep red-purple skin and crisp white flesh; the colour holds when sliced raw into salads.
- Guardsman
- Vigorous cross between a spring onion and a bunching onion: upright dark leaves, long white shanks and a long pulling period.
Spring onions month by month
Timings are for central England. Allow two weeks later in the north and on cold, heavy soil.
- January
Nothing to do. Overwintered rows sit under a cloche in cold areas.
- February
Late in the month, sow in modules under cover, 6 to 8 seeds per cell, for the earliest crop.
- March
First direct sowing under fleece. Plant out module clumps. Start pulling overwintered onions.
- April
Sow every three weeks. Pull overwintered onions before they run to seed.
- May
Sow. Pull the first spring sowings. Water in dry spells.
- June
Sow. Pull as needed, largest first.
- July
Sow in light shade if it is hot. Keep rows watered; dry plants turn hot and tough.
- August
Last summer sowing early in the month. Sow winter-hardy varieties from late August.
- September
Sow White Lisbon Winter Hardy for spring. Pull summer sowings.
- October
Pull the last summer sowings. Cover overwintering rows with mesh, or a cloche in cold gardens.
- November
Nothing to do.
- December
Nothing to do.
Feeding spring onions
A quick, light-feeding crop. In soil that has been fed for other vegetables it usually needs nothing extra; one light base dressing covers a bed that has not.
A light balanced feed is plenty, it's a quick crop that rarely needs much.
Feeding plan
A week before the first sowing, beds
Fruit & Vegetable Fertiliser 4-5-6
70 g/m², the lowest label rate, raked in: 35 g for a patch of half a square metre, which is enough for a season of sowings. Later sowings in the same bed need no more.
At sowing, pots and troughs
Fruit & Vegetable Fertiliser 4-5-6
5 g per litre of compost mixed through: 50 g for a 10 litre trough. Top up with 2 g per litre (20 g) before each resowing in the same compost.
Signs to watch
Yellowing leaf tips and slow growth on poor ground
Nitrogen short
One light top-dress of the dry feed in the feeding plan, watered in
Thick, bulbous bases and coarse flavour
Left too long or overfed
Pull earlier and sow more often
Pale, floppy plants in a pot
Waterlogged compost
Improve drainage, never a feeding problem
Pests, diseases and problems
Leaves pale and yellowing from the tip, then covered in grey-purple felt and collapsing, in damp weather
Onion downy mildew, at its worst in dense, overwintered and late summer sowings
Sow thinly so plants stand 1 to 2 cm apart, water in the morning at soil level, pull and bin affected plants, and sow the next batch in a different spot.
Plants yellow, wilt and pull up with no roots; white fluffy mould on the base
Onion white rot in the soil
No cure, and the fungus persists for many years. Stop growing alliums in that soil and grow spring onions in pots or troughs of bought compost instead.
Lines of white dots on the leaves, which then curl and twist; maggots or brown pupae in the stem
Allium leaf miner, active in March to April and again in October to November
Cover sowings that are in the ground during those months with fine insect mesh. Summer sowings pulled by September escape it.
Seedlings wilt and die in patches in early summer; white maggots at the base
Onion fly
Fine mesh over the row from sowing. Sow thinly so no thinning is needed, since the smell of bruised seedlings attracts the fly.
Leaves flecked silver-white and dull in hot, dry weather
Onion thrips
Water regularly, since damage is worst on dry plants, and pull the crop promptly. It rarely matters on a crop this quick.
Harvest and rotation
Harvest and storage
Pull when 15 cm tall and pencil-thick, 8 to 10 weeks from sowing, taking the largest first to let the rest fill out; loosen with a hand fork so the roots come away cleanly. A 1 m row yields 60 to 80 plants. Use within a week from the fridge in a plastic bag; chop and freeze any surplus.
Rotation and companions
Rotation: allium group, but as a quick crop it slips into gaps between other crops; a 3-year gap. Keep away from beans and peas, which resent allium roots.
Good to knowSow little and often for a continuous supply right through the season.
Growing spring onions in pots
Spring onions are one of the best vegetables for containers. Any pot, trough or window box at least 15 to 20 cm deep will do, filled with peat-free multipurpose compost. Scatter seed thinly across the surface so seedlings stand about 2 cm apart, cover with 1 cm of compost and water with a fine rose. A 60 cm window box gives 40 to 50 onions per sowing. Sow a new container every three weeks, or resow each one as it is cleared, and keep the compost moist, because dry spring onions turn pungent and tough. Pots also avoid onion white rot, which lives in garden soil.
Spring onions: common questions
Can you regrow spring onions from the shop?
Yes. Keep the bottom 3 cm with the roots attached, stand the pieces in a glass with the roots in water on a windowsill, and new green leaves grow within a week. For more than one or two cuts, plant them 5 cm apart in a pot of compost, where they regrow several times.
Do spring onions turn into onions if you leave them?
Not into proper storing onions. White Lisbon types swell into a small, soft bulb and then flower; they can be used like a mild onion but will not keep. Japanese bunching types such as Ishikura never bulb and simply get thicker, like a small leek.
Can you grow spring onions all year round?
Almost. Sowings every three weeks from March to August give onions from May to October, and a winter-hardy variety sown in late August or September is pulled from March to May. Only midwinter is bare, unless you sow in an unheated greenhouse or polytunnel in September.
Sources
Growing information on this page was checked against these references in November 2026. Feeding rates are Dr Forest label rates.