All annual flowers live for one year. Some of the varieties can be grown in all areas of the United States, while others are limited to the warmer parts of the country. Other annual flowers are grown differently in different planting zones and some grow as perennials in one place and annuals in others. The main determining factor is how similar the hardiness zone is to where the plant grows naturally.
Spider flower (Cleome hassleriana) is native to South America. The plant grows from 3 to 6 feet tall and 1 to 2 feet wide. Pink, white, purple or bi-colored flowers grow in clusters at the tips of the stems and bloom from June to first frost. Compound, green leaves are made up of five to seven lance-shaped leaflets. Plant spider flowers in full sun or partial shade, in soil that is moist to dry and well-drained. Spider flowers should be planted outdoors after last frost in warmer areas. In other areas, start the seeds indoors six to eight weeks before the expected last frost. The plant will self-seed very extensively by itself. Collect the pods when they first turn brown, and keep the seeds for next year before they scatter all over the garden. Hummingbirds and butterflies will come by for the nectar, and birds will make a meal out of the seeds.
Angel's trumpet (Datura inoxia var. quinquecuspida) grows as a perennial in USDA zones 9 and 10, where it is a native plant, and as an annual in zones 5 to 8. The plant grows up to 3 feet tall and 6 feet wide with white or pale-lavender, trumpet-shaped flowers 8 inches long and 6 inches across. The flowers open in the evening and last until noon the next day. The coarse leaves have an unpleasant odor and grow up to 10 inches long and 4 inches wide. The flowers are followed by spiny, round seed capsules. Plant angel's trumpet in full sun or partial shade, in soil that is rich and moist to dry. When growing the plant as an annual, start the seeds indoors in late winter or dig up the root in the fall and replant it in the spring.
Strawflower (Bracteantha bracteata) is also known as everlasting daisy and golden everlasting, and is native to Australia.The plant is a warm-weather annual and likes long, hot summers. The flowers resemble a daisy with yellow, pink, bronze, cream, purple or white petals and a yellow center; they measure 2 inches across and grow as singles or in clusters. Thin, lance-shaped gray-green leaves grow up to 5 inches long, and the plant reaches a height of 3 to 4 feet. Plant strawflower in full sun, in soil that is moist, well-drained and allowed to go dry between watering. The seeds can be sown directly into the garden after the last frost in zones 8 and 9. In colder zones, start the seeds indoors from six to eight weeks before the expected last frost and put outside when the soil temperature is close to 55° F. In zones 10 and 11, plant the seeds outside in the fall for blooms in the spring.