What is the proper care and are they healthy
It would be helpful to know where you are located (in the U.S. or world) prior to answering this question. In general, sunflowers are planted from seed when soil temperatures are above 60 degree. They have few disease or insect problems and are excellent cut flowers.
Here is more information from the University of Minnesota: http://www.extension.umn.edu/garden/yard-garden/flowers/sunflowers/