Well, I'm not in NC, but I would suggest a trial "mini-greenhouse. I would build a frame, on the ground, anchored securely, then use some kind of framing, either a "roof truss" sort of contraption, or pvc pipe bent and anchored to the frame, or 1 or two cattle panels bent and anchored to the frame. Then just stretch a UV stabalized plastic over the hoops and secure to the frame. It would only have to be large enough to grow a few plants to experiment with, but large enough to capture some heat. You could use some type of reflective material on the north side to help reflect some light back on the plants. You could also cover the ground inside with black plasitc, and stack some straw bales or some other insulating stuff on the outside of the north wall of the structure. You could make a small access door that you can open on warmer days. Perhaps using a good heavy duty velcro. Put a thermometer inside so you can monitor the temperature every day. These are all things I want to do, but have not gotten around to yet. You could even make it sort of a "pit greenhouse" by having the inside lower than the outside ground level.

Good luck
Kathy in Illinois

Kathy's suggestions are all excellent. Bear in mind that you probably won't get much growth of anything at temperatures less than 50 degrees. Low light is a problem for us in the north. I've rigged up a few mirrors on a frame to bounce light back onto the plants. It works but if you have close neighbors, some may begin to question your sanity. Try greens, broc, cabbage,kale, mustard, tatsoi. Grow root crops in the fall and pick all winter.

Main thing is to try a whole lot of experiments and see what works. Good luck!

Timf7 has it right. Call your extention service. There is a formular to figure the amount of sunlight you will need to grow plants. I use 8'pvc hoops over a raised bed. Have grown plants in 22 degrees for 3 nights without a lose. The main thing is the sun light. At my latatude, things stop growing about the 10th of Nov. If you want to harvest in the winter, they must be almost to their full growth by that date.

How experienced do you need to be? I live in Piedmont NC and grow a kitchen garden in a coldframe on the southfacing wall of my house. Other than fall sowing mesclun mix, lettuce, spinach, English peas, and alliums, I don't do much out in my regular garden. I allow mustard greens to go to seed and pick them rather closely in the reguar garden. They usually keep us in greens with no covering until temps dip below 20 degrees.

Build a semi-solar heated house with a small built in "green-house" facing south-west.

I would grow something like broccoli and Alaskan spinach in this area which could be kept at 45 to 55 degrees - maybe warmer with a paper and wood burning stove.. and/or some compost under the plants.

This is all experimental, but I guess others have tried similar things..

I do guess that this will be more successful in NC than PA..

Brian,
Howdy from just south of Raleigh in Garner! I checked out your web page, pretty cool! I teach Social Studies in Johnston Co. and grow veggies for market in the summers.
As for growing under plastic in the piedmont, sunlight is no scarce resource here. The main problem is venting on sunny days. Eliot Coleman's "Winter Harvest Manual" would have most of the info you need to answer your questions. Basically, when day length goes below 10 hrs., plants go dormant. Being a science teacher you may already know this. So for 35-36 degrees latitude, this is December 1 to around January 10. Sowing dates for fall are such that you want your plant to be mature before this date/first real fall freeze. Coleman has a whole system that works like gangbusters in the north b/c the natural cold helps to store the veggies in the ground all winter and he justs harvests at will. Here in NC we would have to vent tunnels all the time and some growers I have talked to have had some pest problems b/c the tunnel proves to be like a micro climate for pests like flea beetles. I have sucessfully overwintered several things with just Typar spun bonded fabric. Contact me if you are interested in talking shop!
tom

As an NC State grad I know we have an extensive extension service all throughout NC. I know they'd be more than willing to give you some ideas.

I live in NC Piedmont. The normal temperture in my greenhouse on a winter day is around 50 degees. On a really sunny day it can get into the low 70's. In the nights it will fall as low as the tem. outside the greenhouse. But my greenhouse is less then 1 foot away from the brick wall of my house which would up the temperture some. Hope this info helps.

There is an season extention workshop in Chatham co in September.
Here is a link

Here is a link that might be useful: workshop