Tithonia are half hardy annuals that range from 60 cm to 1.2 m in height.
They bloom from summer through to autumn when they carry flowers reminiscent of sunflowers; flowers may be yellow, orange or red.
Some common names for Tithonia include Mexican Sunflower and Golden flower of the Incas.
Common Names: Mexican Sunflower, Tree Marigold, Mexican Tournesol.
Life Cycle: Half hardy annual. Hardy perennial.
Height: 24 to 100 inches (60 to 250 cm).
Native: Central and Northern America.
Growing Region: Zones 3 to 10.
Flowers: Summer and autumn.
Flower Details: Yellow, red, orange. Ray and disc florets. Sunflower-like.
Foliage: Deltoid. Lobed.
Sow Outside: Surface. Following the last frost in warm areas. Spacing 24 to 40 inches (60 to 100 cm).
Sow Inside: Germination time: one to two weeks. Temperature 70°F (21°C). Seven or eight weeks before expected last frost. Transplant outdoors a couple of weeks after the last frost.
Requirements: Full sunlight. Light soils. Can survive in dry soils. Provide support. Water in dry periods.
When growing Mexican Sunflower and other Tithonia plants it is best to start them off indoors unless you live in a very warm area. Start off about 7 or 8 weeks before you expect the last frost of winter / spring. The Mexican sunflower seeds should be sown on the soil surface, and will take from half to two weeks to germinate at a temperature of about 20 degrees centigrade.
The young seedlings of Mexican sunflowers should be transplanted outdoors following the last frost of spring at a spacing of around 60 cm apart. Tithonia species should be grown in sunny areas of the garden and like a light soil.
It is quite easy to care for Mexican Sunflowers and other Tithonia plants. They are quite tall so provide them with a stake, they like hot dry areas, so only provide with water during drought. As Mexican sunflowers are annuals they should be grown from seed, so don't take cuttings or divide the plants for purposes of propagation.