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Marigolds interplanted with tomatoes to stop nematodes: does it work?
Sources (0)
Folklore-unproven Popular claim without supporting field evidence, or tested and not supported.
Planting a few marigolds among vegetables has not been shown to protect them from root-knot nematodes in field conditions.
- Krueger R. et al. Marigolds (Tagetes spp.) for Nematode Management. UF/IFAS Extension ENY-056/NG045.
- Soil Organic Matter, Green Manures, and Cover Crops for Nematode Management. UF/IFAS Extension ENY-059/VH037.
Mechanism
Claimed: root exudates protect neighbors. In practice nematodes still find susceptible roots.
What the research found
- UF/IFAS: interplanting "does not appear to be effective"; an intercrop with cucurbit reduced cucurbit yield with no nematode effect (Powers et al. 1993, cited in NG045).
- One positive result was in pots, where soil dilution may explain it (El-Hamawi et al. 2004, cited in NG045).
- UF/IFAS VH037: such plants "rarely, if ever, protect plants from nematodes when planted among or beside them".
Caveats
Interplanting may even risk crop damage while giving a false sense of protection.
How to try it
Use marigold as a solid cover crop before the vegetable instead (see the cover-crop page).
Other Folklore-unproven pairings (4)
- Tomato and basil
- Tomato and Brussels sprouts ("bad neighbors")
- Nasturtium as an aphid trap crop
- Mint to repel garden pests
Evidence summary checked 2026-10-14. We cite only peer-reviewed studies, university extension and USDA/ARS sources; results may differ in your region. Not professional advice.