It is as beautiful as it is rare. A frost is created on autumn or early winter mornings when ice in extremely thin layers is pushed out from the stems of plants or occasionally wood. This extrusion creates wonderful patterns which curl and fold into gorgeous frozen petioles giving this phenomenon both its name and its appearance.
Conditions have to be just so for frost form. Early winter and late autumn are the optimum time to come across them as although the weather conditions must be freezing it is vital that the ground is not'.
Source and Image: http://www.kuriositas.com/2012/12/frost-flowers-natures-exquisite-i...