Tithonia, along with sunflowers, are the largest, most dramatic annuals for the garden. Some varieties can grow up to 8 feet tall. A native of Mexico and southward, its area of origin is the reason for its common name. Members of the daisy family, they are also related to the sunflower.
Description of tithonia: Tithonias have rough, hairy leaves on tall, vigorous plants. Shorter varieties are now available that will stay approximately 4 feet tall. The flowers are single and up to 3 inches in diameter. The color is a deep orange-red, even though there is now a variety with chrome-yellow flowers.
Growing tithonia: Tithonia must have full sun, but it will grow in average soil with good drainage. It is one of the most heat- and drought-resistant plants, growing reasonably well in soils of low fertility. Plant in the garden after all danger of frost has passed. Space plants 21/2 to 3 feet apart. Do not overwater. Protect the plants from high winds and stake them -- this is particularly important in late summer and fall when they are tall and top-heavy.
Propagating tithonia: By seed. Seeds may be sown outdoors; for earlier flowering, start them indoors 6 to 8 weeks earlier. Seeds germinate in 7 to 21 days at 70 degrees Fahrenheit.
Uses for tithonia: Its size and coarseness of the foliage dictates planting it at the back of the border. The color is so intense that it only takes a few plants for impact. It is also useful for covering fences and shielding background eyesores in the garden. Tithonias make good cut flowers as long as the hollow stems are seared after cutting and plunged into 100 degrees Fahrenheit water.
Tithonia related varieties: Torch is a medal winner that grows 4 to 6 feet tall, bearing the classic, deep orange-red flowers. Yellow Torch has yellow flowers. Fiesta del Sol is true orange. Goldfinger is a compact orange to 4 feet.
Scientific Name of Tithonia: Tithonia rotundifolia