This fact brought to you by quarantine.
As far as I can determine, based on the very limited facts I have found in a star chart book my family got me awhile back (Cardassia’s star is -1.1 in absolute magnitude and has K0V spectral classification) and information on Wikipedia, regarding spectral classification, habitable zones, orbital period equations, and such.
The Cardassian year is likely much longer than an Earth year, and would be between 32.56 and 102.22 Earth years in length, with a greater likelihood of being at or below 40 Earth years in length.
Full explanation below cut: