Some zinnias are annuals and live only one year. Others are perennials and bloom more than one year. Zinnias grow best in a warm, sunny climate and deep, sandy soil. The seeds should be planted in early spring after the danger of frost has passed. The seeds can also be planted inside in late winter and transplanted outside in spring.
Zinnias flower in midsummer to late summer.
Zinnias make up the genus Zinnia in the composite family, Asteraceae or Compositae. David J. Keil, Ph.D., Professor of Botany, California Polytechnic State University. How to cite this article.