october

There are many, many different ways and opinions about overwintering evergreens. Some feel thet they need almost no light in winter, others feel that they need some light in the winter. I, personally, have never deprived my evergreens of light in the winter.
I usually keep them in a cold hallway where the temp is usally 10-20 degrees higher than it is outside. So if its 15 f degrees outside, its usally 30-45f in the hall. Also, they get about 2-4 hours of filtered sun a day. Keep in mind that the temp and light have to be proportional. If they are kept in an area that is 15-35 degrees all winter, they probably wouldn't need too much light.
I don't have any experience on over wintering in the ground, but I believe that you could bury the pot and all into the ground.
This winter, I am thinking of trying something different. I have a shed in the back yard with 3 windows, 2 north and one west. The inside receives about 2-3 hours of sun. The temp in the shed would be colder than the hall that I usually use. The temp is probably only 5-15 degrees warmer than the outside.
I would start a new thread asking about the techniques that other members with more wintering experience than myself, use. I can, however, offer some important guide lines to follow:
1) the best temperature for evergreens in the winter is between 30-40 degrees fahrenheit

2) Do not let the temerature rise above 49 degrees f for any long period of time (2-3 days). Also, do not let it drop to below 15 degress for any long period of time.

3) Try to keep them away from harsh, drying winter winds.

4) Dormancy must always be a gradual thing. Leave them out throuh the first frost or 2, probably till around thanksgiving, then gradually lessen the light they get, until they are in their winter place for the winter.

I hope my advice has been beneficial.