French Marigold Companion Plants
Tagetes patula · aster family family · rotation group: other
The best companion plants for french marigold are Tomato, Squash, Pepper and Pepper. Of the 4 pairings recorded here, 2 are supported by published research and 1 is traditional practice with no controlled evidence behind them.
What to plant with french marigold
| Plant | Claimed benefit | Evidence | What the evidence actually shows |
|---|---|---|---|
| Squash | Marigolds interplanted with squash reduce pest pressure. | Research-backed | UMN Extension cites a Florida study in which marigolds were effective with squash; UMN's overall verdict on marigolds is candid, sometimes yes and sometimes no. |
| Tomato | French marigolds interplanted with tomatoes slow glasshouse whitefly population growth. | Research-backed | Supported by controlled trials, with two hard caveats: the work was done in glasshouses, not open gardens, and marigolds only worked when present from the start; added after whitefly had built up they gave minimal benefit. The active compound is airborne limonene. |
| Pepper | Marigolds bordering peppers reduce pest pressure. | Traditional | Plausible via general floral diversity; no pepper-specific trial found. |
What not to plant with french marigold
| Plant | Claimed problem | Evidence | What the evidence actually shows |
|---|---|---|---|
| Potato | Marigolds deter Colorado potato beetle. | Not supported | Directly tested and rejected: UMN Extension states that many gardening articles mention marigolds as a deterrent for Colorado potato beetles, but multiple studies have shown this to be untrue. |
The honest verdict
Of everything gardeners recommend planting alongside french marigold, 2 pairings have been tested properly: Tomato, Squash. Those are the ones worth planning your bed around.
The remaining 1 pairing on this page is traditional practice. They circulate on every companion planting chart online, but we could not find controlled evidence testing them. They are not wrong so much as unverified — most cost nothing to try, and interplanting flowers and herbs has its own well-documented benefit of pulling pollinators and predatory insects into the garden.
Widely repeated, not supported: Potato — Directly tested and rejected: UMN Extension states that many gardening articles mention marigolds as a deterrent for Colorado potato beetles, but multiple studies have shown this to be untrue.
Every row above links to the publication it came from. See how we grade evidence.
Other recorded effects
7Effects that aren't about a neighbouring plant — what french marigold does for (or to) the garden around it, and the caveats attached to the popular versions of those claims.
| Effect | The claim | Evidence | What the evidence actually shows |
|---|---|---|---|
| Nematode-Infested Bed (as a cover crop) | A solid season-long stand of Tagetes patula grown as a cover crop suppresses root-knot and lesion nematodes in that soil. | Research-backed | Genuinely supported, but only in this precise form: UF/IFAS specifies marigold must be planted as a dense solid stand at least two months before the vegetable crop, with plant and row spacing under 7 inches (about 289 plants per 100 square feet). It is a rotation treatment for the bed, not a neighbour for a crop. |
| Thrips (as a trap crop) | Scented French marigolds draw thrips, slugs and snails away from crops so they can be removed. | Traditional | WSU Extension Master Gardeners list French marigold as a trap crop for thrips, nematodes and slugs; it works by attracting pests, not repelling them, and must be actively monitored. |
| Pollinators and Predators | Marigolds provide season-long bloom that supports generalist predators and pollinators. | Traditional | Bloom is long and reliable, but marigold performed no better than water as a nectar source in a controlled parasitoid feeding trial, so do not assume it feeds parasitic wasps. |
| Thrips on Tomato | Marigolds interplanted with tomatoes reduce thrips numbers. | Research-backed | UMN Extension reports a few studies show marigolds can be effective at reducing thrips populations; note this is thrips specifically, not the broad pest protection usually claimed. |
| Scattered Marigolds for Nematode Control | Popping a few marigolds between tomatoes controls root-knot nematodes. | Not supported | Directly contradicted: UF/IFAS states that intercropping marigold with other crops to reduce plant-parasitic nematodes does not appear to be effective, because nematodes simply find and reproduce on the roots of the susceptible crop growing alongside. |
| Aphid Control | Marigolds repel aphids from the vegetable garden. | Not supported | Marigolds attract rather than repel aphids and are sometimes used deliberately as an aphid trap crop; the limonene effect demonstrated in trials was against whitefly, not aphids. |
| Signet Marigold (T. tenuifolia) for Nematodes | Any marigold works against nematodes. | Not supported | Species and cultivar matter: signet types such as Golden Gem and Tangerine Gem are susceptible hosts to all three major root-knot species and will increase nematode populations. |
Growing french marigold: the numbers
| Sun | Full sun (6+ hours) |
|---|---|
| Water | Moderate |
| Spacing | 8 in apart · 12 in between rows · 4 per square foot |
| Mature size | about 10 in tall |
| Soil pH | 6–7 |
| Days to maturity | 45–60 days |
| Frost tolerance | Tender — killed by frost |
| Containers | Yes — 1 gallon minimum |
| Common pests | spider mites, thrips, slugs |
| Common diseases | powdery mildew, botrytis, leaf spot, root rot |
When to plant french marigold
Zone 6b shownStart seeds indoors: Feb 13 – Mar 13 — 4–8 weeks before your last frost
Transplant outdoors: Apr 17 – Apr 30 — 1 week after last frost
Direct sow outdoors: Apr 17 – Apr 30 — 1 week after last frost
Expected harvest: Jun 1 – Jun 16 — 45–60 days from planting
Those dates are for zone 6b. Get your own dates by ZIP code →
Varieties worth knowing
seeds- Single Gold — UF/IFAS-listed as resistant to all three major root-knot species; used in nematode cover-crop trials
- Tangerine — UF/IFAS-listed resistant T. patula selection for nematode suppression
- Dwarf Primrose — another UF/IFAS-listed resistant French marigold
- Bolero — avoid for nematode work: rated intermediate, and UF/IFAS warns intermediate types are unpredictable
Variety names link to seeds on Amazon. As an Amazon Associate we earn from qualifying purchases. These are the varieties named in the extension sources for this crop, not a paid placement — where a source recommended a variety for a specific reason, that reason is the note beside it.
Put it in a bed
The garden planner checks every square against this ledger as you place crops — if you drop french marigold next to something recorded as a bad neighbour, the square turns red and tells you why.
Records for the plants named above:
Same rotation group (other) — don't follow one with another:
French Marigold companion planting questions
What should not be planted next to french marigold?
How far apart should french marigold be planted?
Does companion planting with french marigold actually work?
When should I plant french marigold?
Sources for this record
- Tagetes patula, NC State Extension Gardener Plant Toolbox
- Marigolds (Tagetes spp.) for Nematode Management, UF/IFAS EDIS ENY-056
- Companion planting in home gardens, University of Minnesota Extension
- Marigolds, University of Minnesota Extension
- Wolfe, K. (2020), Trap Cropping, WSU Extension Master Gardeners
Record compiled 2026-07. Spot an error or a study we missed? Tell us and we'll correct the entry.