Tagetes patula

• RawWhole plantExternalTraditional use

  Classic companion-planting and green-manure use of French marigold: roots release phototoxic thiophene derivatives that suppress root-knot and lesion nematodes — long-standing horticultural practice repeatedly confirmed since the 1970s.

  Preparation & dosage

  COMPANION PLANTING / GREEN MANURE against nematodes: Sow Tagetes patula as a companion between tomatoes, potatoes, strawberries or beans — spacing 25–30 cm. Root exudates (α-terthienyl and other thiophene derivatives, plus polyacetylenes) inhibit migrating root-lesion nematodes (especially Pratylenchus penetrans and Meloidogyne spp.). Effect appears after 2–4 months — leave plants for the whole season for sustained soil clearance, then cut above ground and work residues into the soil (green manure). Solid pre-cropping (sole stand) in an infested bed is more effective than scattered individuals.

  Sources: [1] [2] [4]

• TeaFlowerInternalFolk medicine

  Traditional Mexican infusion of dried florets — reported for stomach cramps, flatulence and menstrual complaints. Not established outside Mexican folk medicine; no EMA or Kommission E assessment.

  Preparation & dosage

  FOLK INFUSION (Mexican tradition): Pour 200 ml boiling water over 1–2 g dried T. patula florets (stems removed), cover and steep 5–10 min, strain. 1–2 cups daily for mild stomach cramps, flatulence or menstrual complaints. Use SHORT-TERM only — max 1 week; consult a doctor for persistent symptoms. NOT in pregnancy (described as emmenagogue/uterotonic in folk use). Avoid with Asteraceae allergy. Taste reminiscent of tarragon (from the essential oil).

  Dry amount

  1–2 g

  Doses per day

  2×

  Max duration

  1 weeks

  ⚠ Age restriction: ≥ 12 years — Internal use not for small children — folk preparation without pharmacopoeial dossier.

  Sources: [1] [6]

• CompressFlowerExternalFolk medicine

  Folk skin compress (Mexico, Andean countries): for mild skin irritation, superficial wounds, traditionally also against scabies and skin parasites. Note phototoxicity from α-terthienyl.

  Preparation & dosage

  INFUSION compress: Pour 250 ml hot water over 3–5 g dried florets, steep 10 min, strain, cool to skin temperature. Soak a clean cotton or linen cloth and apply for 20–30 min to irritated or mildly inflamed skin. 1–2× daily. DO NOT apply before direct sun exposure — thiophene derivatives (α-terthienyl) are phototoxic and may cause erythema, blistering or burning in combination with UV-A.

  Dry amount

  3–5 g

  Doses per day

  2×

  Max duration

  1 weeks

  ⚠ Age restriction: ≥ 12 years — Due to phototoxicity and lack of paediatric data, only from 12 years; always covered from sunlight.

  Sources: [1] [3] [6]

• BathFlowerExternalFolk medicine

  Traditional partial bath for skin fungus and callus problems — antifungal action of the essential oil (α-terthienyl is active against dermatophytes) shown in vitro, not clinically standardised.

  Preparation & dosage

  HAND/FOOT BATH: Pour 2 L boiling water over 30–50 g dried T. patula florets and herb, steep 15 min, strain, add to lukewarm bath (hand or foot). Bathe 10–15 min. Avoid direct sun for at least 6 hours after bathing (phototoxicity). Traditionally used in Mexico for foot fungus, corns and tired legs.

  Dry amount

  30–50 g

  Doses per day

  1×

  Max duration

  1 weeks

  ⚠ Age restriction: ≥ 12 years — Not for young children due to phototoxicity.

  Sources: [5] [6]

• SpiceFlowerInternalTraditional use

  Culinary use (Georgia, Imereti region): dried ground ray florets are a traditional yellow spice — known as 'imeruli shaphrani' or Imeretian saffron. Also used industrially to colour egg yolks and poultry feed.

  Preparation & dosage

  DRIED PETALS AS SPICE: Harvest fully opened flower heads, air-dry, pluck off the ray florets, grind to powder in a mortar. In Georgia known as 'imeruli shaphrani' ('Imeretian saffron') and part of the Khmeli Suneli blend — pairs with chicken, rice and walnut dishes. A knife-tip per portion. Provides intense golden-yellow colour and a mild earthy-aromatic taste. Culinary use, not medicinal.

  Sources: [1]

• Essential oilFlowerExternalTraditional use

  Tagetes essential oil: spot-applied, strongly diluted on calluses, corns or fungal nails. Phototoxic via α-terthienyl and α-bithienyl — strict sun avoidance after use required.

  Preparation & dosage

  TAGETES OIL (strongly diluted): 1 drop of Tagetes oil (T. patula or T. minuta) in 20 ml carrier oil (almond, jojoba) — about 0.1–0.25 % dilution. IMPORTANT: SCCS opinion sets max. 0.01 % Tagetes oil in leave-on cosmetics (excluding sunscreen), and α-terthienyl content of the oil must not exceed 0.35 %. Higher home-made concentrations are only acceptable for rinse-off use (short contact, then washed off) or for spot application followed by sun avoidance (24–48 h). NEVER apply on large areas before sun exposure — phototoxicity (erythema, blistering) otherwise. Classically dabbed on corns, calluses and toenail fungus.

  ⚠ Age restriction: ≥ 18 years — Adults only — narrow safety window because of phototoxicity.

  Sources: [2] [3] [5]

Tagetes patula essential oil and root exudates contain thiophene derivatives, mainly α-terthienyl (α-T) and α-bithienyl — these are PHOTOTOXIC: combined with UV-A light they can cause erythema, blistering and contact dermatitis. Avoid direct sun for 24–48 hours after external use of T. patula infusions, baths or oil; or keep treated areas covered. The EU SCCS (2019) set a maximum of 0.01 % Tagetes oil in leave-on cosmetics (excluding sunscreens) — follow this benchmark. Avoid with known Asteraceae allergy (mugwort, ragweed, chamomile) — cross-reactions possible. Internal use is folk medicine only, with no EMA or Kommission E assessment — keep short-term and at low dose. Per the UNAM ethnobotanical database, horses are reportedly sensitive to large amounts of fresh T. patula material (mouth/skin irritation via thiophenes) — avoid as a companion in horse pastures.

⏱ Max continuous use: 1 weeks