Bidens is part of a group consisting of hardy perennials and annuals, commonly called Bur Marigolds. These plants belong to the aster/daisy family, Asteraceae/Compositae, and are found wild in southern U.S., Mexico and Guatemala. Their common names include: shepherd's needles, Spanish needles, Bidens pilosaand butterfly needles.
They grow from 1 to 3 feet high, with a 12 inch or so spread. B. ferulifolia is a perennial that forms clumps of divided, fern-like, green leaves. The starry, golden yellow flowers are 11/2 inches across. According to the info I found on the Internet, the plants produce abundantly from mid-spring to the first frost. However, I covered my Bidens during our last freeze and they survived without loosing a bloom.
Grow these plants in full sun, in well-drained soil. They are great for planting in a border, hanging baskets, and other containers. B. ferulifolia may be grown as an annual. These plants may be increased by seeds, division, or stem cuttings in the spring.
Here, the patch of Bidens is about 6 months old. I like how it softens the edge of the driveway. The plant comes from tropical America, but it spread to Asia and the Pacific many years ago and is now widely naturalized throughout the tropics and subtropics everywhere in the world. Bidens thrives in gardens, farm fields and open areas. It will flower and reseed profusely whether you want it to or not -- but nothing attracts more butterflies! The blossoms are a favored nectar source for many species. However, be forewarned - it is considered a very invasive plant. Either grow it in a container or, if you put it in a bed, make sure you can contain it. Pay attention and keep it trimmed so it doesn't get out of hand.