my zenias are withering in india.please advice?

Answer 1

Once Zinnias flower and go to seed then they are finished. I plant zinnia every spring and they are always the first to go.
Save the seed by collecting the dried flowers and store them in a cool dark place until spring and then you can toss them on the soil and they will germinate right there.

Answer 2

They are either thirsty, or they are done. Zinnias are annuals. They grow, bloom, and then die. If they are finished blooming, they may simply be finished. You can save the seeds from the seed pods that appear after the flowers fade, and save them for planting next season.