When to Plant Spring Onions in the UK

On this page
  1. Spring onion (Allium fistulosum)
  2. Watch: Growing Spring Onions at Home
  3. Quick Facts
  4. At a Glance
  5. Regional Planting Calendar
  6. Growth Stages
  7. Soil & Growing Conditions
  8. Harvest & Storage
  9. Regrowing From Kitchen Scraps
  10. Diseases
  11. Pests
  12. Companion Planting
  13. Spring Onions, Seed to Harvest
  14. Plan your Spring Onions planting
  15. Growing Spring onion in another region
  16. References
  17. Frequently Asked Questions
  18. Spring Onions in brief: the short answer

Sow spring onions in succession from March to August for a continuous harvest through spring, summer and autumn, or sow a hardy variety in late summer to overwinter for an extra-early crop the following spring.

The short answer

Plant
Early March to late September
Ready in
60 days
Site
5+ hours of sun, soil pH 6.6–7.4
Biggest risk
Onion downy mildew

Core growing advice on this page is checked against named horticultural sources — see References.

Spring onion (Allium fistulosum)

Freshly pulled spring onions with white bases and green tops on a board. Photo: Kolforn, CC BY-SA 4.0, via Wikimedia Commons.

10 sources cited · Verified

Watch: Growing Spring Onions at Home

A step-by-step SoilCommander video on growing perfect spring onions at home in the UK — sowing, spacing, care and harvest.

Quick Facts

A bunch of freshly harvested green onions with roots, white shanks and green tops — “Beijing scallions” by Fumikas Sagisavas is licensed under CC0. Source: Wikimedia Commons
“Beijing scallions” by Fumikas Sagisavas is licensed under CC0. Source: Wikimedia Commons.
Factor Value
Soil pH 6.6 - 7.4
Sunlight 5-5 hours direct sun
Optimal growing temp 12-25°C
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

A single unopened Allium fistulosum flower bud among green leaves — “Allium fistulosum in Botanical Garden of Besançon002” by Krzysztof Golik is licensed under CC BY-SA 4.0. Source: Wikimedia Commons
“Allium fistulosum in Botanical Garden of Besançon002” by Krzysztof Golik is licensed under CC BY-SA 4.0. Source: Wikimedia Commons.
Allium fistulosum Spring onion Onion downy mildew Allium leaf miner Leek moth Onion fly Stem and bulb nematode DISEASES PESTS

Regional Planting Calendar

A young Allium fistulosum plant growing in soil, identification label visible — “Allium fistulosum - Copenhagen Botanical Garden - DSC07943” by Daderot is licensed under CC0. Source: Wikimedia Commons
“Allium fistulosum - Copenhagen Botanical Garden - DSC07943” by Daderot is licensed under CC0. Source: Wikimedia Commons.
Region Sow
Southern England early March to late September
Midlands derived mid March to mid September
Northern England derived early April to early September
Scotland derived mid April to early September

Rows marked derived are interpolated between regions our sources do state, because no source we consulted gives a figure for that region specifically. They are deliberately wider to reflect that uncertainty.

Southern England - detail & sources

Sow small batches every couple of weeks from March through to about September for a continuous supply; sow hardy varieties in late summer/early autumn to overwinter for a spring crop. Southern England has the UK's earliest soil-warming and last frosts (Met Office), so the earliest March sowings and the longest season apply here.

Midlands - detail & sources

DERIVED: the successional sowing window opens about two weeks later than southern England and closes a little earlier, as the Midlands warm later and cool sooner (Met Office south-to-north gradient). Hardy autumn sowings still overwinter for spring.

Northern England - detail & sources

DERIVED: sowing starts about a month later than southern England (from April) and ends by early September, reflecting the Met Office south-to-north gradient. Start under cover for an earlier crop.

Scotland - detail & sources

DERIVED: the latest and shortest window - sow from about mid-April to early September, as Scotland is slowest to warm and cools earliest (Met Office). Modules under cover extend the season at both ends.

A page from the UK Vegetable Garden Planner PDF: the crop rotation planner, with a planning grid and four-bed rotation tips

Plan your spring onions — and the rest of the plot

This page covers spring onions. For every crop's sowing months on one chart, use the free UK vegetable planting calendar, and browse the UK vegetable growing guides for what else to grow alongside it. When you want the whole season on paper, the UK Vegetable Garden Planner is a printable PDF:

  • Twelve month-by-month sowing and harvest spreads
  • Raised bed, allotment and container layout pages for your own plot
  • A four-year crop rotation planner
  • Seed inventory, sowing log and harvest tracker
See inside the UK Vegetable Garden Planner →

80 printable pages · instant PDF download · reprint every season

Growth Stages

Allium fistulosum plants in flower, with round white pom-pom flowerheads on tall stems — “Allium fistulosum 2” by Dalgial is licensed under CC BY-SA 3.0. Source: Wikimedia Commons
“Allium fistulosum 2” by Dalgial is licensed under CC BY-SA 3.0. Source: Wikimedia Commons.
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.

Soil & Growing Conditions

Rows of spring onions growing in ridged soil in a field — “Bunching onions growing in a field” by Miyuki Meinaka is licensed under CC BY-SA 4.0. Source: Wikimedia Commons
“Bunching onions growing in a field” by Miyuki Meinaka is licensed under CC BY-SA 4.0. Source: Wikimedia Commons.

Water: RHS: water young plants until established, "then only water during prolonged dry spells"; container plants need more frequent watering. Univ. of Maryland: "Ensure ample moisture, especially after bulbs begin enlarging".

Soil pH range

6.6 7.4

Span reflects genuine variation between the cited authorities, not a single agreed figure.

Harvest & Storage

A crate of bunched red and white salad onions at a market — “Spring onions at a market in Gallicano” by Kritzolina is licensed under CC BY-SA 4.0. Source: Wikimedia Commons
“Spring onions at a market in Gallicano” by Kritzolina is licensed under CC BY-SA 4.0. Source: Wikimedia Commons.

When to pick: RHS: pull salad onions when "about 15cm (6in) tall, with the bulb no more than 1-2.5cm (½-1in) across". Univ. of Maryland independently agrees on the same benchmark: "Harvest green onions when tops are 6 inches tall".

Regrowing From Kitchen Scraps

Spring onions regrowing from cut white bases in a pot — “Scallions regrowing” by Daderot is licensed under CC0. Source: Wikimedia Commons
“Scallions regrowing” by Daderot is licensed under CC0. Source: Wikimedia Commons.

A store-bought bunch doesn't have to end at the chopping board. Save the white base with its roots -- trim about 2.5cm (1in) above the roots -- and stand it upright in a glass or shallow dish, with just enough water to cover the roots. Illinois Extension: "Save the bulbs (the white part with roots) of your green onions... place in a shallow dish of water... Place in a sunny window and watch as new greens emerge from the top of the bulb." UC Agriculture and Natural Resources adds the one real caution -- don't use chlorinated water -- and reports full-sized regrowth in about a month on a warm, bright windowsill. Change the water every couple of days as it clouds. It's a genuinely free extra crop, but flavour and vigour fade after a few regrowth cycles; for a steady long-term supply, transplant the regrowing base into soil, or start a fresh batch from seed.

Diseases

Onion downy mildew
moderate

Peronospora destructor

RHS names "salad onions" (spring onions) among affected hosts.

Pests

Allium leaf miner
high

Phytomyza gymnostoma

RHS: affects "Leeks, onion, chives, shallot and garlic". [Allium genus-wide RHS pest pages explicitly name multiple Allium crops including chives/shallot; reused for other Allium species in the graph.]

Leek moth
moderate

Acrolepiopsis assectella

RHS: affects "Leek, onion, shallot, garlic". [Allium genus-wide RHS pest pages explicitly name multiple Allium crops including chives/shallot; reused for other Allium species in the graph.]

Onion fly
moderate

Delia antiqua

RHS onion fly page: affects "Onion, shallots, and leeks". [Allium genus-wide RHS pest pages explicitly name multiple Allium crops including chives/shallot; reused for other Allium species in the graph.]

Stem and bulb nematode
high_where_present

Ditylenchus dipsaci

RHS names onions among affected vegetables; Allium family members "swell and distort (onion blout)". [Allium genus-wide RHS pest pages explicitly name multiple Allium crops including chives/shallot; reused for other…

Companion Planting

avoid shared disease

Allium sativum

Both crops are documented hosts of Onion downy mildew. These pathogens persist in soil for many years -- RHS gives up to 20 years for club root resting spores, at least 15 years for allium white rot sclerotia, and advises a five-year gap before replanting onions or shallots after downy mildew --…

avoid shared disease

Allium cepa

Both crops are documented hosts of Onion downy mildew. These pathogens persist in soil for many years -- RHS gives up to 20 years for club root resting spores, at least 15 years for allium white rot sclerotia, and advises a five-year gap before replanting onions or shallots after downy mildew --…

avoid shared disease

Allium cepa Aggregatum Group

Both crops are documented hosts of Onion downy mildew. These pathogens persist in soil for many years -- RHS gives up to 20 years for club root resting spores, at least 15 years for allium white rot sclerotia, and advises a five-year gap before replanting onions or shallots after downy mildew --…

Plan your Spring Onions planting

When to sow and plant Spring Onions depends on your own frost dates. Check the UK vegetable planting calendar, or the month-by-month guides that cover Spring Onions: May, June, July, August, September. To work out where it fits in your beds, sketch your plot in the free Garden Layout Planner.

Growing Spring onion in another region

Sowing dates, frost timing and local advice differ by country. Use the guide for where you garden.

References

  2. 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.

  10. 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 32-40°F 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

When should I sow spring onions in the UK?

In Southern England, from early March. In Scotland, wait until mid April. Treat these as a guide rather than a fixed date — the governing rule is to sow only once frost risk has passed and temperatures are reliably warm enough.

When do I sow spring onions?

Sow early March to late September.

How long do spring onions take to grow?

Typically 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

Most of the advice on this page comes down to timing and spacing — sowing at the right moment, rotating beds, and giving plants enough airflow. The UK Garden Planner lays your plot out month by month so those decisions are already made before the season starts.

Get the UK Garden Planner →

Instant PDF download · Written for UK growing conditions

SoilCommander Editorial Team — under the direction of Nitin Sharma, Co-Founder

Every growing guide is checked against RHS, USDA Cooperative Extension, and other named horticultural authorities before publishing.

How this guide is put together

The growing data on this page — sowing windows, pests, diseases, soil and site requirements — comes from named horticultural sources, listed in References below, checked against RHS and Met Office guidance. An automated pipeline assembles that verified data into the page you're reading: it selects which facts to lead with and builds the surrounding prose and layout. It does not invent a date, a source or a number — where a verified value for a field isn't available, the page leaves it out rather than guessing. A person reviews and publishes each page; nothing goes live unverified.

Vegetable Growing Guides UK

Crops With the Same Problems

Last verified 2026-09-02

Quick answer

Spring Onions in brief: the short answer

To grow spring onions in the UK, sow thinly in drills or containers from spring onwards, keep seedlings watered, and harvest young stems as soon as they are large enough to use. Spring onions fit well between slower crops because they take little space and can be sown in repeat batches.

Succession crop Sow small rows every few weeks instead of one large batch.
Space saver Use bed edges, containers, and gaps between slower-growing vegetables.
Harvest young Pull when stems are usable and tender so the crop keeps moving through the season.
Watch the spring onion growing guide

This video supports the page with a practical look at sowing and growing spring onions at home, especially for small spaces and repeat sowings.

Watch the spring onion video on YouTube

Use the UK vegetable planting calendar to plan repeat sowings. Use the UK Vegetable Garden Planner PDF to track small-space sowings, harvests, and follow-on crops.

Relevant next steps

Where To Go From Here

Take this crop from reading into a written plan for your own beds.

UK garden plannerTurn this crop guide into sowing dates, bed layouts and a harvest record. All growing guidesBrowse every crop we cover for your region, A to Z. Planting CalendarSee how this crop fits alongside everything else you are growing.

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