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Entire healthy mature french marigold plant in a real garden bed, showing growth habit and scale.Primary identification image. 20–45 cm tall, 20–30 cm wide at maturity.

French marigold

Tagetes patula L.

Also called: Tagetes, African marigold (T. erecta, related)

Family
Asteraceae
Season
Warm-season tender annual
Best grown in
Portland, Oregon

The most-cited companion flower, with two genuinely different evidence stories: glasshouse whitefly on tomato, and root-knot nematodes in soil.

Safety: Sap can irritate skin.

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Life cycle & growth stages

  1. 1. SeedSow indoors 4–6 weeks before last frost or direct after it.
  2. 2. SeedlingEmerges in 5–7 days.
  3. 3. TransplantSet out after frost.
  4. 4. FloweringOrange and yellow flowers from 8 weeks to frost.
  5. 5. DeadheadingRemove spent blooms weekly.
  6. 6. SeedDry heads yield seed for next year.

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 1–3 weeks after last frost; direct sow 1–4 weeks after last frost; 50–60 days to maturity from sowing. 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.

French marigoldTagetes patula
PlantStart indoorsDirect sowAutumn sowTransplantTendHarvest
French marigoldFeb 22–Mar 8 (estimate)Apr 12–May 3 (estimate)—Apr 12–Apr 26 (estimate)May 3–Jun 1 (estimate)Jun 1–Nov 5 (estimate)
  • Start seeds indoors: Feb 22 – Mar 8
  • Transplant outdoors: Apr 12 – Apr 26
  • Direct sow: Apr 12 – May 3
  • Tend and monitor: May 3 – Jun 1
  • Harvest: Jun 1 – Nov 5

Spacing & support

In-row 20–30 cm; rows 30–30 cm. Planner footprint: 1 cell of 30 cm.

Side-profile diagram of mature french marigold: canopy 20–45 cm tall, 20–30 cm wide, shallow root zone, support and harvest-access envelope.

Soil & water

Soil
Any well-drained soil
pH
6–7
Fertility
low
Water
Moderate; tolerates short drought.
Frost
tender; killed by frost

Support & training

No support structure needed.

French marigold mid-season before harvest, showing branching, vining, rosette or upright habit and space occupied.

Harvest signs

  • Deadhead spent flowers to prolong bloom
  • Collect seed from dry heads
French marigold at harvest readiness, showing the visual cues: deadhead spent flowers to prolong bloom; collect seed from dry heads.

Common problems

Pests: slugs, spider mites, aphids

Diseases: Botrytis in wet weather

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

Side-by-side: healthy french marigold leaf or fruit and an example of Botrytis in wet weather.

Container growing

  • Minimum 3 L (15 cm deep)
  • Use quality potting mix and water more frequently
Mature french marigold in a correctly sized container (3 L or more) with drainage visible.

Companion overview

6 reviewed relationship records (evidence: medium).

Supported or conditional

Carrot, Tomato

Avoid or separate

None with evidence

Traditional claims only: Bush beans, Cabbage.

1 popular pairing reviewed with no verified relationship.

Full companion profile

Crop rotation

Avoid planting french marigold or other daisy family crops in the same spot for 1 year. Rotation is about previous seasons, not about live neighbours.

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

Shared risks in Asteraceae: lettuce downy mildew, aphids, slugs on lettuce.

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 french marigold

French marigolds are sown indoors 4–6 weeks before the last frost or directly after it, flower within 8 weeks and keep flowering until frost if deadheaded. They are compact (20–45 cm), tolerate poor soil and are easy in containers.

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

Two evidence strands are often merged into one "marigolds repel pests" claim. Conboy et al. (2019) showed that French marigolds interplanted with tomatoes in a glasshouse reduced whitefly, through airborne limonene; the effect may be weaker outdoors where volatiles disperse. Separately, Tagetes roots suppress some root-knot nematodes, but mainly when marigolds are grown as a dense cover crop for a season before the susceptible crop (Hooks et al. 2010), which is a rotation practice, not a neighbour effect.

Two or more mature french marigold plants with a tape measure showing in-row spacing (20–30 cm).
French marigold flower detail or bolting stage.
Immature petals of french marigold developing on the plant.

Marigolds are hosts for slugs and spider mites and their open single flowers are visited by hoverflies; double-flowered cultivars offer less.

Edible parts and safety

Edible: petals (sparingly). Sap can irritate skin.

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

Pests and diseases

Common pests: slugs, spider mites, aphids. Common diseases: Botrytis in wet weather. These vary by region; a photograph is an example, not a diagnosis. See the pest and disease guides and your local extension service.

slugs on french marigold, with a wider damage-context view.

Timeline

Season timeline for french marigold: sowing, transplanting, flowering, harvest and bed occupancy aligned to frost dates.Text alternative: Start seeds indoors Feb 22–Mar 8; Transplant outdoors Apr 12–Apr 26; Direct sow Apr 12–May 3; Tend and monitor May 3–Jun 1; Harvest Jun 1–Nov 5.

Related plants

See also: Asteraceae 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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