When considering winter in Colorado, I often want to write that plants rest, but in fact, I don't think that is true. A rest is defined as a time to relax and recover strength. Plants drop their leaves and go dormant in winter because they cannot move ice in their tissues, let alone use it to grow. Furthermore, water expands as it freezes, so freezing rips up most cells. There is no recovery of strength in winter, only waiting out an impossible season.
That said, the plants that survive through the winter are an elite minority.