Rob S. aka Blitz wrote:
...Dig a large are out of the ground that is at least 3 feet deep which should get me close to the frost line, the dug out area will slope from North to South so it will receive max sun exposure in the winter and allow for cooler air to run down to the bottom of the slope.
I plan to put large rocks on the north, east and west sides that will act as thermal mass and wind breaks.
Once the cool weather comes around I will heavily mulch up to a foot around the base of the plants and even cover them.
I also will build a simple triangle shaped cover that will have a glass face that will point towards the south. The back interior of it will be reflective to bounce sun rays back against the glass and intensify the solar energy.
I use a simple method to protect several satsuma trees here in my orchard in upstate SC. Put 4 tee-posts around the sides of the tree. Place several water filled gallon milk jugs around the base of the tree. Wrap a water heater insulation blanket around the outside of the tee-posts to surround the tree, then pull a large leaf collection bag down over the top of the entire assemblage. Leave the tree covered until after last frost to keep it from breaking dormancy too soon. When dormant, satsumas are leaf hardy into the upper teens F, but once they have broken bud, those same leaves (and the new growth) can be killed by any below freezing temps.
They are in complete darkness for about 3 months, but it doesn't bother them since they are dormant. Think about an evergreen tree surviving through a winter in the British Isles. It gets less than 8 hours of daylight with the sun spending most of that time near the horizon and behind a thick cloud bank most of the time. Very little photosynthesis gets done during that time of year even on evergreens.