Known commonly as Spanish needles and beggarticks, Bidens are members of the Asteraceae family. Grown across the United States as an annual weed, these pretty cousins of the cosmos bedding flower are airy and delicate. The thin stems of the Bidens bear dark green leaves that terminate in a cluster of daisy-like flowers with wider, papery leaves and a bright yellow center. Proper soil preparation and maintenance during the growing season will ensure more blooms and lush, full Bidens plants.
Prepare the planting bed to encourage larger, healthier Bidens blooms. Incorporate up to 4 inches of organic matter, such as well-rotted manure, into the bedding soil and cultivate 6 to 8 inches deep.
Add a balanced slow-release fertilizer to the tilled soil. A 10-10-10 analysis applied at the rate of 2 lbs. per 100 square feet of bed is suggested by the horticulture experts at the University of Illinois Extension.
Plant in the spring when the soil is able to hold moisture. Soggy or hard, crumbly soil are both poor media for growing Bidens. After planting, keep soil moist to encourage growth and blooming.
Pinch off spent blooms immediately. This is the single most important step in encouraging more blooms on your Bidens plant. If spent blooms are allowed to remain on the stem, the plant will spend valuable energy producing seeds rather than growing new flowers. Use a bucket to catch the dead flowers and empty in the compost bin if the flowers are healthy, or the waste can if disease is suspected. Disposing of dead plant material carefully is a good way to promote health and stop the spread of disease in your garden.
Fertilize with an annual flower liquid mix at the manufacturer suggested rate every six to eight weeks after planting to promote larger, more profuse flowers from your Bidens.