Bidens should get at least six hours a day of full sunlight. Plant in fertile, well drained soil with a pH between pH 5.5 and 6.3. Once they are established, bidens are quite drought tolerant, but a too-long period of drought can affect their blooming potential so water them about once a week for an extended bloom. The temperature tolerance depends on the variety. Most bidens do fine with hot and humid temperatures, but will die back when it dips below 5 degrees C. Other varieties of bidens are winter hardy even in cold climates.