Zinnias are annual flowers that produce blooms for one season before dying. They must be replanted if a gardener wishes to enjoy the flowers the next year.
Zinnias are available in a variety of colors and textures. Heights range from 12 to 30 inches, so they can be planted in the front or back of flower groupings. They prefer warm temperatures, fertile soil and lots of sun. Zinnias should be planted after the last frost, and they begin to grow quickly, germinating within seven days if temperatures are between 70 and 75 degrees Fahrenheit. Care should be taken to protect zinnias from powdery mildew. They are very vulnerable to this disease.