Tobacco can cure with a green cast if temperatures during curing drop below 60^oF while the tobacco still has 
some chlorophyll.  The pictures below were from the 2002 crop.  The green was set the second weeks in October
 as temperatures dropped into the upper 40's at night.  Delay in maturity brought on by excess nitrogen accumulation 
in the plant at harvest can increase the chances of having a green cure.