My wife is from Bulgaria, and her name is Zdravka. Her parents told her that "Zdravka" comes from the flower ZDRAVETZ. She has shown me this flower growing around Sophia, Bulgaria. According to my google-image searching, I think the flower might be a type of geranium (Geranium macrorrhizum):http://en.wikipedia.org/wiki/Geranium_macrorrhizumI hope that helps!
Folk etymology likes to derive this name from Bulgarian здравец (geranium).