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Entire healthy mature brussels sprouts plant in a real garden bed, showing growth habit and scale.Primary identification image. 60–100 cm tall, 45–60 cm wide at maturity.

Brussels sprouts

Brassica oleracea var. gemmifera DC.

Family
Brassicaceae
Season
Cool-season biennial grown as an annual
Best grown in
Portland, Oregon

A tall, slow brassica planted in late spring for harvest after autumn frost; it occupies its space for most of the year.

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Life cycle & growth stages

  1. 1. SeedSow indoors 4–6 weeks before last frost.
  2. 2. SeedlingGrow cool and bright.
  3. 3. TransplantSet out firmly; stake.
  4. 4. Mid-growthTall stem with large leaves.
  5. 5. Sprouts formingBuds swell in leaf axils from the base.
  6. 6. Harvest readyFirm 2–4 cm sprouts after frost.
  7. 7. HarvestTwist off lower sprouts; pick the top as greens.

Growth stages are ordered chronologically; timing varies with cultivar, temperature, light and care.

Planting calendar for Portland, Oregon

Start indoors 4–6 weeks before last frost; transplant 2 weeks before to 3 weeks after last frost; 90–120 days to maturity from transplant. Windows are derived from the region's average frost dates (last Apr 5, first Nov 5) and are estimates until you confirm your own dates in the calendar.

Brussels sproutsBrassica oleracea var. gemmifera
PlantStart indoorsDirect sowAutumn sowTransplantTendHarvest
Brussels sproutsFeb 22–Mar 8 (estimate)——Mar 22–Apr 26 (estimate)Apr 26–Jun 20 (estimate)Jun 20–Oct 19 (estimate)
  • Start seeds indoors: Feb 22 – Mar 8
  • Transplant outdoors: Mar 22 – Apr 26
  • Tend and monitor: Apr 26 – Jun 20
  • Harvest: Jun 20 – Oct 19

Spacing & support

In-row 60–60 cm; rows 75–90 cm. Planner footprint: 4 cells of 30 cm.

Side-profile diagram of mature brussels sprouts: canopy 60–100 cm tall, 45–60 cm wide, medium root zone, support and harvest-access envelope.

Soil & water

Soil
Firm, fertile loam
pH
6.5–7.5
Fertility
high
Water
Steady water through summer.
Frost
very hardy; tolerates frost

Support & training

Stake in exposed sites. Install at planting so roots are not disturbed later.

Brussels sprouts trained on its support: stake in exposed sites.

Harvest signs

  • Sprouts 2–4 cm, firm and tight
  • Harvest from the bottom up
  • Flavour improves after frost
Brussels sprouts at harvest readiness, showing the visual cues: sprouts 2–4 cm, firm and tight; harvest from the bottom up.

Common problems

Pests: cabbage aphid, cabbage white caterpillars, whitefly, cabbage root fly

Diseases: clubroot, leaf spot

Appearance alone is not a diagnosis; confirm with a regional extension guide.

Side-by-side: healthy brussels sprouts leaf or fruit and an example of clubroot.

Container growing

Too tall and long-lived for most containers.

Companion overview

1 reviewed relationship record (evidence: medium).

Supported or conditional

None reviewed

Avoid or separate

None with evidence

Full companion profile

Crop rotation

Avoid planting brussels sprouts or other cabbage family crops in the same spot for 3 years. Rotation is about previous seasons, not about live neighbours.

Year 1Year 2Year 3BrassicaceaeOther familyOther familyback after 3+ years

Shared risks in Brassicaceae: clubroot, cabbage root fly, cabbage white caterpillars.

Crop rotation hub

Sources, reviewer & update

Sources

Reviewer: Garden Planner editorial team (pending independent horticultural review)

Last reviewed: August 15, 2026 · version 1

Found an error or have feedback? Let us know.

Growing brussels sprouts

Brussels sprouts need 90–120 days from transplanting and taste best after frost, so they are planted in late spring or early summer for a late-autumn harvest. Firm soil and staking keep the tall stems upright in wind.

Brussels sprouts seed beside a ruler or coin for scale.
Brussels sprouts seedling at cotyledon and first-true-leaf stage, in soil, distinguishable from common weeds.
Brussels sprouts mid-season before harvest, showing branching, vining, rosette or upright habit and space occupied.

Sprouts form in leaf axils from the bottom up; harvest lower sprouts first and remove yellowing leaves. Plants reach up to a metre and shade neighbours on the north side.

Two or more mature brussels sprouts plants with a tape measure showing in-row spacing (60–60 cm).
Brussels sprouts flower detail or bolting stage.
Immature buds of brussels sprouts developing on the plant.

This is the crop in Bomford's tomato study: tomatoes and Brussels sprouts are traditionally listed as enemies, but the field trial found no harmful pairing, only ordinary competition at high density.

Edible parts and safety

Edible: buds (sprouts), leaves, tops.

Hands or tool harvesting brussels sprouts correctly (cut, pull, twist or pick) without damaging the plant.

Pests and diseases

Common pests: cabbage aphid, cabbage white caterpillars, whitefly, cabbage root fly. Common diseases: clubroot, leaf spot. These vary by region; a photograph is an example, not a diagnosis. See the pest and disease guides and your local extension service.

cabbage aphid on brussels sprouts, with a wider damage-context view.

Timeline

Season timeline for brussels sprouts: sowing, transplanting, flowering, harvest and bed occupancy aligned to frost dates.Text alternative: Start seeds indoors Feb 22–Mar 8; Transplant outdoors Mar 22–Apr 26; Tend and monitor Apr 26–Jun 20; Harvest Jun 20–Oct 19.

Related plants

See also: Brassicaceae family page · crop rotation · regional calendar · guides

Our Methodology & Sources

We synthesize peer-reviewed research, university extension publications, and trusted horticulture resources. Our evidence levels help you understand how strong the science is behind the guidance.

Evidence tiers

Supported evidenceConsistent results from multiple robust studies
Traditional claimHistorical use reported, limited scientific support
Context dependentMixed or variable results across conditions
No verified relationshipNo reliable evidence identified

Primary source types

  • Peer-reviewed journal articles
  • University extension publications
  • Government & research institute reports
  • Systematic reviews & meta-analyses

Last updated

August 24, 2026

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