The Latin specific epithetpatula means “with a spreading habit”.
Physical characteristics
The flower is an annual, occasionally reaching tall by wide. In some climates it flowers from July to October. In its native habitat of the highlands of central Mexico, blooms are produced from September to killing frost. Achenes ripen and are shed within two weeks of the start of bloom. The heads contain mostly hermaphrodite florets and are pollinated primarily by beetles in the wild, as well as by tachinid flies and other insects. The leaves of all species of marigold include oil glands. The oils are pungent. It can grow in both sandy and clay soils provided they have good drainage. It requires growing in sunlight. Resists cold well to -1°C ; from there it is sensitive to frost and does not develop in the shade.
Cultivation
This plant is valued for its velvet-textured, brightly coloured blooms in shades of yellow, orange and brown in summer. It is shorter, and has a more spreading habit, than its relative the African marigold. It is therefore more suitable as an edging plant in the open border. The plant is used in companion planting for many vegetable crops. Its root secretions are believed to kill nematodes in the soil and it is said to repel harmful insects, such as white flies on tomatoes.
Cultivars
Hundreds of cultivars have been developed, of which the following have gained the Royal Horticultural Society's Award of Garden Merit:-
'Aurora Light Yellow'
Bonanza Series
'Dainty Marietta'
'Disco Orange'
'Disco Yellow'
'Hero Orange'
'Honeycomb'
'Queen Sophia'
'Safari Mixture'
'Safari Scarlet'
'Safari Tangerine'
'Strawberry Blonde'
'Tiger Eyes'
'Yellow Jacket'
Other uses
Medicinal
Medicinally, many cultures use infusions from dried leaves or florets. Research also suggests that T. patula essential oil has the ability to be used as residual pesticide against bedbugs. The essential oil is being investigated for antifungal activity, including treatment of candidiasis and treating fungal infections in plants.
Tagetes patula florets are grown and harvested annually to add to poultry feed to help give the yolks a golden color. The florets can also be used to color human foods. A golden yellow dye is used to color animal-based textiles without a mordant, but a mordant is needed for cotton and synthetic textiles.
Fragrance
The whole plant is harvested when in flower and distilled for its essential oil. The oil is used in perfumery. It is blended with sandalwood oil to produce 'attar genda' perfume. About of oil can be extracted from of the plant yielding of flowers and of herbage.