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Variety profile · Onion

Growing Hercules: large onions, early flowering and a carefully dried harvest

Hercules is described as having large, strongly flavoured bulbs. Follow the difference between bulb growth and bolting, read source differences about shape and discover what storage needs after lifting.

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AI illustration of Hercules
AI illustration

This image was created with AI from described plant characteristics and growing advice. It shows a possible situation and is not a photograph of a verified cultivar.

Location
Sunny, airy and free-draining
Start
Seed and onion sets have different schedules
Onion set
Root base down; tip just visible above the soil
Harvest
Foliage naturally yellow and fallen over; then dry carefully

This growing advice helps you choose. Your variety, growth stage, weather and conditions in your space determine the actual timing.

A good start

Sowing under cover and raising seedlings

Start under cover in a cool, bright position · Onion

February–March for seed-grown onionsSow lightly in modules or a seed tray and grow on steadily.

Germination and temperature
Germinate under cover, then grow on in good light without excessive warmth.
After emergence
Give seedlings light immediately after emergence. A dark loft needs suitable grow lights; warmth alone is insufficient. Ventilate and keep the compost moist without saturating it.
Pricking out and potting on
Sow in modules or a seed tray. Move young plants with their root ball according to cultivar guidance; a small group of spring onions can stay together.
Hardening off and planting out
Gradually acclimatise indoor-raised plants to sun, wind and outdoor temperatures; shelter them again on cold nights. Plant out sturdy young onions at suitable final spacing. Seed-grown onions are plants raised from seed; onion sets are planted directly.

Onion sets and seed-grown onions are different starting routes. Bunching and spring onions are generally harvested young.

Sources and use

Royal Horticultural Society · RHS — ui kweken ↗Soort- of productgebonden bron; buitenlandse perioden zijn geen vaste Nederlandse zaaidatum.

University of Minnesota Extension · UMN Extension — ui in de moestuin ↗Soort- of productgebonden bron; buitenlandse perioden zijn geen vaste Nederlandse zaaidatum.

Guideline periods for the Netherlands and Flanders. Check the variety, available light, soil and measured temperatures. Greenhouse heating does not guarantee enough winter light.

Compare how to raise other vegetables →

What makes Hercules different?

Fruit shape
Almost roundUnited Kingdom
Fruit size
LargeUnited Kingdom
Height
50-100 cmUnited Kingdom
Light
Full sunUnited Kingdom
Main colour
Dark golden brownUnited Kingdom
Resistances
Good resistance to bolting; flowering remains possibleUnited Kingdom
Open-pollinated / F1
F1-hybrideUnited Kingdom
Save
Stores well with suitable harvesting, drying and storageUnited Kingdom
Flavour
Strong flavourUnited Kingdom
Width
10-50 cmUnited Kingdom

The source context and any limitations are in the background information at the bottom.

Compare with another variety
How it could look in your garden

How to grow onion

The options below belong to the plant. From these, choose the method that suits your variety's growth habit.

AI illustration of plantuien in een overzichtelijk bed
AI illustration

This image was created with AI from described plant characteristics and growing advice. It shows a possible situation and is not a photograph of a verified cultivar.

Onion sets in a manageable bed

Small planting bulbs make an accessible start. The tip stays visible and the root base gets loose soil.

  1. Choose healthy planting material for the intended season.
  2. Prepare a clean bed and space bulbs upright according to the variety.
  3. Leave the tip just above soil; do not press hard into dense ground.
  4. Weed carefully, check moisture and lift bulbs when foliage matures naturally.

For a simple start and a batch of storage onions.

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AI illustration of uien uit zaad voor meer raskeuze
AI illustration

This image was created with AI from described plant characteristics and growing advice. It shows a possible situation and is not a photograph of a verified cultivar.

Onions from seed for greater variety choice

Sowing opens more choice but needs time for young shoots. Start timing must suit variety and intended planting position.

  1. Sow thinly in modules or a fine seedbed as the variety advises.
  2. Give plenty of light and keep the young root zone moist.
  3. Thin or plant sturdy seedlings at the recommended spacing.
  4. Let bulbs and foliage mature normally and select healthy produce for drying.

For anyone following the whole process with a suitable seed-grown variety.

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AI illustration of een kleinere voorraad uit een brede bak
AI illustration

This image was created with AI from described plant characteristics and growing advice. It shows a possible situation and is not a photograph of a verified cultivar.

A smaller stored crop from a wide container

Onions can grow in a broad container if every bulb has enough room. A container makes weeding easy but needs more frequent moisture checks.

  1. Choose a wide container with unrestricted drainage and airy compost.
  2. Plant healthy onion sets or seedlings at normal spacing.
  3. Water evenly during growth and remove weeds early.
  4. Let foliage fall naturally and dry the harvest away from wet compost.

For a sunny balcony or patio and a limited stored crop.

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Leave the tip just visible
AI illustration

This image was created with AI from described plant characteristics and growing advice. It shows a possible situation and is not a photograph of a verified cultivar.

Take a closer look

Leave the tip just visible

Put onion sets into the soil root-end down. The bulb belongs in the soil; only the dry tip stays above the surface.

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A large bulb starts with a precise variety profile

The RHS describes Hercules with large, almost round, dark golden-brown bulbs; guidance gives strong flavour. This is a recognisable choice, not fixed onion weights. Keep labels from planting to compare flavour, shape and bed conditions later.

Two descriptions do not say exactly the same thing

The 2011 historical RHS list gives Hercules slightly elongated bulbs, while the profile says almost round. Retain this difference without inventing an intermediate shape. Record actual plants. Photos supplement profiles without re-proving old trials.

Less prone to bolting is not a free pass

The RHS growing guide lists good bolting resistance for Hercules. Its cultivar profile also mentions bolting as a possible problem. That is no reason to stop checking. Resistance describes a limited property; it does not rule out flowering. Watch for a developing flower stalk and keep unusual plants identifiable in your records.

A flower stem serves a different purpose for the plant

Onions are biennial, but cold may trigger early flowers before stems show. Heat-treated sets may reduce risk. Record purchased stock. Flowering does not prove wrong variety names; conditions belong to the story too.

Monitor growth where the roots are

General onion care needs attention to shallow-root moisture. Check reachable soil and weed gently. Automatically increasing feed does not guarantee leaves or bulbs; excess late nitrogen can harm maturity and storage. Assess crops and soil before repeating care.

A large onion also needs steady ripening

For storage onions, await natural yellowing and flopping; do not bend foliage yourself. Lift gently and separate damaged bulbs for earlier use. Size is one trait; soundness and maturity help determine uses. Storage selection starts while gathering.

Let the harvest air before packing

Dry bulbs thoroughly. Papery skins, dry roots and necks indicate readiness. Protect from rain and do not rely solely on dates. Handle a few bulbs individually to inspect. Good-storage descriptions do not replace this step, even for large varieties.

Keep the experience alongside the last onions

Inspect soft and sprouting onions and use first. For Hercules, record bolting and stock treatment too, helping change one choice next time. Historical sources call it F1; saved seed therefore does not guarantee identical stock for comparing crops.

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More background, sources and image information

SeedSteps editorial team · updated on 11 October 2026. The AI images illustrate species and practical growing situations; they do not prove an exact cultivar, observations from your own garden or yield.

Britse gewasadviezen worden gecombineerd met Nederlandse en Vlaamse informatie waar beschikbaar. Amerikaanse Extension-bronnen ondersteunen plantprincipes en herkenning; hun kalenderdata, lokale plaagdruk, bestrijdingsmiddelen en mestdoseringen worden niet rechtstreeks op Nederland of Vlaanderen toegepast. Vorst, bodemwarmte, standplaats en expliciete rasinformatie blijven de lokale controle. Commerciële bronnen onderbouwen uitsluitend benoemde ras- en plantkenmerken; zij zijn geen affiliate-aanbeveling.

  1. World Checklist of Vascular Plants — 4 juni 2026Royal Botanic Gardens, Kew · accessed 2026-10-07
  2. Common catalogue of varieties of vegetable species — 27 januari 2023Europese Commissie · accessed 2026-10-07
  3. Hercules: rasprofielRoyal Horticultural Society · accessed 2026-10-08
  4. Uien: zaaien, planten, oogsten en bewarenRoyal Horticultural Society · accessed 2026-10-08
  5. Uien en knoflook: historische RHS-rasbeschrijvingen uit 2011Royal Horticultural Society · accessed 2026-10-08
  6. Handboek Schooltuinen: raskeuze en plantuiHandboek Schooltuinen, via Velt · accessed 2026-10-08
  7. Ajuin doux de Florence ras van Simiane zaden biologischFeggies · accessed 2026-10-11
  8. Ajuin rood van Abbeville zaden biologischFeggies · accessed 2026-10-11
  9. Ajuin Stuttgart zaden biologischFeggies · accessed 2026-10-11
  10. Ui Sturon 500gram BiologischFeggies · accessed 2026-10-11
  11. Ajuin wit uit Lisboa zaden biologischFeggies · accessed 2026-10-11
  12. Shakespeare Gele Herfst Ui - 250gr BiologischFeggies · accessed 2026-10-11
  13. Doorschieten: van groei naar voortijdige bloeiRoyal Horticultural Society · accessed 2026-10-08
  14. Growing onions: wortels, verzorging en bewaringUniversity of Minnesota Extension · accessed 2026-10-08
  15. Zelf groentezaad bewaren: open bestoven en hybride rassenUniversity of Minnesota Extension · accessed 2026-10-08
  16. Onions in the Garden: teelt en oogstUtah State University Extension · accessed 2026-10-08
  17. Red Baron: Nederlandse zaai- en bewaaraanwijzingenDe Bolster · accessed 2026-10-08
  18. RHS — ui kwekenRoyal Horticultural Society · accessed 2026-10-10
  19. UMN Extension — ui in de moestuinUniversity of Minnesota Extension · accessed 2026-10-10
  20. Fenologische kalender: tuinieren met het seizoenVelt · accessed 2026-10-08

Supporting evidence by chapter: A large bulb starts with a precise variety profile: Royal Horticultural Society, Royal Horticultural Society. Two descriptions do not say exactly the same thing: Royal Horticultural Society, Royal Horticultural Society. Less prone to bolting is not a free pass: Royal Horticultural Society, Royal Horticultural Society. A flower stem serves a different purpose for the plant: Royal Horticultural Society. Monitor growth where the roots are: University of Minnesota Extension. A large onion also needs steady ripening: Royal Horticultural Society. Let the harvest air before packing: Utah State University Extension, Royal Horticultural Society. Keep the experience alongside the last onions: Utah State University Extension, Royal Horticultural Society, University of Minnesota Extension.

Fruit shape: Almost round Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society

Fruit size: Large Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society

Height: 50-100 cm Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society

Light: Full sun Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society

Main colour: Dark golden brown Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society

Resistances: Good resistance to bolting; flowering remains possible De Britse RHS-teeltgids noemt weerstand tegen doorschieten. Het Hercules-profiel noemt doorschieten als mogelijk probleem; geen immuniteit of ziekteweerstand bedoeld. Royal Horticultural Society

Open-pollinated / F1: F1-hybride Historische Britse RHS-beschrijving, versie maart 2011. Geen introductiejaar, actuele populariteitsranglijst of Nederlandse teeltkalender. Royal Horticultural Society

Save: Stores well with suitable harvesting, drying and storage Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society

Flavour: Strong flavour Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society

Width: 10-50 cm Britse RHS-beschrijving; broncontext geldt voor het rasportret, zonder lokale maat-, oogst- of bewaargarantie. Royal Horticultural Society