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Variety profile · Broccoli

Growing Marathon: follow the dense head and the plant's next growth

Marathon is broccoli with a central, dense main head and its own British variety profile. Discover the F1 designation, give space and follow how harvest stage matters more than a fixed date.

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AI illustration of Marathon
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.

Harvested part
Flower buds still closed
Type
Calabrese or sprouting broccoli
Location
Fertile, well-drained
Harvest
Before flowers open

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 cool conditions in modules or a seedbed · Broccoli

March–May, only for a suitable harvest typeSow somewhere cool and bright and avoid long, weak growth.

Germination and temperature
Germinate under cover, then grow on in cool, bright, well-ventilated conditions; avoid a hot growing space.
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 prick out manageable young plants. Let the root ball firm up without a check in growth.
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 brassicas and protect against cabbage root fly and caterpillars where needed.

Early, summer, autumn and winter cultivars have their own windows. The spring period shown is a basic route; use cultivar guidance for overwintering and winter cauliflower.

Sources and use

RHS · kolen ↗Britse teeltrichtlijn voor een gematigd klimaat; de genoemde perioden zijn richtlijnen voor Nederland en Vlaanderen.

Feggies · Broccoli 'Bobby' Biologisch ↗Nederlandse producent of teeltbron; de rasinstructie blijft leidend.

Feggies · Broccoli calabrese – biologische groentezaden (doorplukker) ↗Nederlandse producent of teeltbron; de rasinstructie blijft leidend.

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 Marathon different?

Variety type
Medium-sized, tightly closed central headsUnited Kingdom
Growth habit
Clump-formingUnited Kingdom
Height
50-100 cmUnited Kingdom
Light
Full sunUnited Kingdom
Main colour
Blue-green central headsUnited Kingdom
Open-pollinated / F1
F1-hybrideUnited Kingdom
Soil
Fertile, firm, non-acidic soilUnited 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 broccoli

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

AI illustration of zomerbroccoli onder gaas
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.

Summer broccoli under mesh

A bed of healthy young plants gives manageable central heads.

  1. Plant at the variety's recommended spacing.
  2. Cover with mesh on sufficiently tall hoops.
  3. Cut the main head, then monitor side shoots.

For a distinct summer or autumn harvest.

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AI illustration of een compact ras in een ruime container
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 compact variety in a large container

A suitable small variety can be tried for a limited harvest.

  1. Check your variety's documented compactness.
  2. Provide a large container with drainage and suitable potting compost.
  3. Keep growth and moisture steady and harvest closed buds.

For limited bed space; open ground remains more practical for larger plants.

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A variety for a central head

The RHS places Marathon among calabrese: broccoli forming a central main head. Its British cultivar list describes firm, blue-green heads. Base your harvest expectations on that. A sprouting cultivar producing several separate shoots develops differently; do not automatically use its calendar or appearance as a model for Marathon.

The seed choice has an explicit reference

Sakata lists Marathon F1 in its British 2025/26 catalogue. Match that variety name on packets. Keep current packaging with notes and record starts, connecting later experience with actual seed lots rather than names read elsewhere.

Consider the plant around the bud

The RHS profile gives fifty to one hundred centimetres height and ten to fifty spread. Look beyond plated broccoli when planning beds. Follow packet spacing and maintain path access. Spread is variety data, not a complete identical-yield layout for every bed.

Give the rootball a gentle transition

British calabrese guidance warns of transplant root disturbance. Use young plants and acclimatise indoor ones first. Observe recovery after planting. Photos and short weather/soil notes explain later differences without tying starts only to dates.

Fertile soil remains a local question

For Marathon, RHS gives full sun and fertile, firm, non-acid soil. Assess local meaning and soil before adding anything. American guidance stresses testing and targeted feeding. Another garden's quantity does not replace your soil and plants' evidence.

The variety profile helps you observe well

The RHS describes medium, dense heads. Follow whether florets remain closed and the main head is usable. Warmth speeds flowering. Visit Marathon deliberately then, even if your schedule says a later harvest. Actual plants signal what planning worked towards.

A healthy appearance does not rule out problems

The British cultivar profile mentions general disease resistance, but does not separately guarantee protection against every brassica disease. Examine leaves and the main head carefully when something changes. Moisture, heat and other conditions can also affect appearance. Record observations and assess a possible cause before choosing a measure; Marathon's name does not remove the need for diagnosis.

Do not let the first cutting exhaust the whole bed

Main-head broccoli may later form smaller sideshoots. Leave plants if following this and observe actual useful shoots. Pick before flowers open too. British long-harvest descriptions become a journal question: how did main and later rounds perform here?

Ready to begin

What you need

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The basics
Propagation
Protection
Harvesting

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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. Calabrese: hoofdknoppen en zijscheutenRoyal Horticultural Society · accessed 2026-10-08
  4. Marathon: rasportret van een zomerbroccoliRoyal Horticultural Society · accessed 2026-10-08
  5. Marathon F1 in de Britse catalogus 2025/26, pagina 12Sakata · accessed 2026-10-08
  6. Broccoli 'Bobby' BiologischFeggies · accessed 2026-10-11
  7. Broccoli calabrese – biologische groentezaden (doorplukker)Feggies · accessed 2026-10-11
  8. Broccoli met paarse spruiten zaden biologischFeggies · accessed 2026-10-11
  9. Broccoli Vert Calabrais zaden biologischFeggies · accessed 2026-10-11
  10. Broccoli: blad, knoppen, verzorgen en bewarenUniversity of Maryland Extension · accessed 2026-10-08
  11. Broccoli: wortelvocht, hoofdknop en volgende plukUniversity of Minnesota Extension · accessed 2026-10-08

Supporting evidence by chapter: A variety for a central head: Royal Horticultural Society. The seed choice has an explicit reference: Sakata. Consider the plant around the bud: Royal Horticultural Society. Give the rootball a gentle transition: Royal Horticultural Society. Fertile soil remains a local question: Royal Horticultural Society, University of Minnesota Extension. The variety profile helps you observe well: Royal Horticultural Society, University of Maryland Extension. A healthy appearance does not rule out problems: Royal Horticultural Society, University of Minnesota Extension. Do not let the first cutting exhaust the whole bed: University of Minnesota Extension, Royal Horticultural Society.

Variety type: Medium-sized, tightly closed central heads Brits RHS-rasportret; opgegeven plantmaat is geen Nederlandse plantafstand of oogstkalender. Royal Horticultural Society

Growth habit: Clump-forming Brits RHS-rasportret; opgegeven plantmaat is geen Nederlandse plantafstand of oogstkalender. Royal Horticultural Society

Height: 50-100 cm Brits RHS-rasportret; opgegeven plantmaat is geen Nederlandse plantafstand of oogstkalender. Royal Horticultural Society

Light: Full sun Brits RHS-rasportret; opgegeven plantmaat is geen Nederlandse plantafstand of oogstkalender. Royal Horticultural Society

Main colour: Blue-green central heads Brits RHS-rasportret; opgegeven plantmaat is geen Nederlandse plantafstand of oogstkalender. Royal Horticultural Society

Open-pollinated / F1: F1-hybride Rasbeschrijving van de veredelaar in de genoemde marktcontext; geen Nederlandse oogstduur of opbrengstgarantie. Sakata

Soil: Fertile, firm, non-acidic soil Brits RHS-rasportret; opgegeven plantmaat is geen Nederlandse plantafstand of oogstkalender. Royal Horticultural Society

Width: 10-50 cm Brits RHS-rasportret; opgegeven plantmaat is geen Nederlandse plantafstand of oogstkalender. Royal Horticultural Society