Green onions (Allium fistulosum)
10 sources cited · Verified
The short answer
- Ready in
- 60–60 days
- Site
- 5+ hours of sun, soil pH 6.6–7.4
- Biggest risk
- Onion downy mildew
In the UK, spring onions are ready to harvest 60–60 days after planting.
Spring onions (Allium fistulosum) — Grown as a fast annual salad crop, pulled young within about two months of sowing.
Unlike an annual crop, the work here is front-loaded into establishment: get the planting and the site right and the same plants crop for several seasons.
Core growing advice on this page is checked against named horticultural and university-extension sources — see References.
Soil & Growing Conditions
Growth Stages
| Stage | BBCH | Notes |
|---|---|---|
| Sowing & Germination | 0 | Spring onions are almost always sown direct where they are to grow. SOWING DEPTH & SPACING: make a shallow drill 1cm (half inch) deep, water along the base, and sow the seed thinly, spacing rows about 20cm (8in) apart; thin seedlings to about 2.5cm (1in) apart. TIMING: sow small batches every couple of weeks from March onwards for a continuous supply through spring, summer and autumn; sow hardy varieties in late summer to early autumn to overwinter for a spring crop. An earlier start is possible from a March sowing in modular trays under cover, and they also grow well in a container at least 30cm (1ft) wide. |
| Leaf & Shank Growth | 3 | Each seedling grows into a slim plant with hollow green leaves and a slender white shank, barely swelling at the base. Water young plants until they are well established, then only during prolonged dry spells (container plants need watering more often as the compost dries quickly). Weed regularly - hoe between the rows and hand-weed between the closely spaced plants - so the shallow-rooted onions are not crowded. |
| Harvest | 8 | Spring onions generally take about two months (roughly eight weeks) to reach harvesting size. Pull them young and mild when about 15cm (6in) tall with the base no more than 1-2.5cm (half to 1in) across - simply lift individual onions with a hand fork whenever you need them, right through spring to autumn. Harvest regularly and successionally rather than all at once, as they do not store and are best eaten fresh. |
| Bolting, Flowering & Overwintering | 6 | Spring onions are grown as a quick crop, but plants left in the ground eventually run up a round white flowerhead (bolting), after which the shanks turn tough - so pull them before this. Hardy varieties sown in late summer or early autumn simply sit through the winter and are pulled the following spring, while Allium fistulosum left to grow on forms a perennial clump that flowers each year and can be divided. |
Quick Facts
| Factor | Value |
|---|---|
| Soil pH | 6.6 - 7.4 |
| Sunlight | 5-5 hours direct sun |
| Optimal growing temp | 12-25C |
| Time to harvest | 60-60 days |
| Drainage | RHS: "Choose a sunny planting site" with "free-draining soil", improved with organic matter. |
| Lifecycle | Grown as a fast annual salad crop, pulled young within about two months of sowing; botanically a hardy biennial to short-lived perennial. Hardy types overwinter to crop the following spring, and plants left in the ground form clumps and flower in a later year. |
| Edible parts | whole young plant (leaves and bulb) |
At a Glance
Harvest & Storage
Diseases
Pests
Companion Planting
Spring Onions, Seed to Harvest
References
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country=INTL
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Qualitative only: southern/coastal last air frost often before end of April; further north well into May, in a few places into June. No numeric per-region frost dates published here.
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country=UK
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country=UK
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country=UK
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country=UK
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country=UK
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country=UK
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country=USA
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Tier 1. US extension source: sow 1/4-1/2 in deep in rows 8-16 in apart, with seeds, sets or transplants 3-4 in apart in the row; green onions harvestable from about 50 days after seeding while bulb onions need 100-120 days; onions bulb under long days and hot weather, and planted too late in spring most will grow leaves and never bulb; green onions can be left at closer spacing and thinned as they are used; leave bulb onions until the tops fall over, then dry 1-2 weeks until skins are papery; store cold at 32-40F and dry.
10 independent sources are cited for this crop. Where they disagree - soil pH is the clearest case - every figure is preserved rather than averaged into false precision.
Frequently Asked Questions
How long do spring onions take to grow?
Typically 60–60 days, depending on cultivar and growing conditions.
What soil pH do spring onions need?
A pH of about 6.6–7.4. That span reflects genuine variation between the authorities we cite rather than a single agreed figure — the References section lists each source's exact range.
What problems affect spring onions?
Our data links 1 disease and 4 pests to this crop. See the sections above for each one and how to manage it.
Plan next season before the problems start
This page gives you the thresholds; the planner turns them into your own calendar. It works from what you can observe and measure in your garden rather than from dates written for somebody else’s latitude.
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