Interesting Notes about Zinnia:

Zinnia is one of the easiest annuals to grow and the reward is constant color for both the garden and bouquets.  The general size of both plants and flowers are specific to the variety, likewise the habit can be sprawling to boldly upright with strong stems.  Hummingbirds and butterflies use the flowers for landing pads and for the nectar.  Native to areas where weather is hot and dry, it is no wonder Zinnia has difficulty with wet or humid conditions.  Powdery mildew quickly affects the plant with splashed water or rain, but even when infected the flowers keep on coming.