help with heating it in the winter

[Brett]

Just curious. I have built a nine foot tall 14 x 20 ft greenhouse. I am getting ready to put on the plastic, and was wondering if I put black plastic on the lower 4 ft if that would help with heating it in the winter, or if it would cut off too much light. Does anybody out there have any idea?
Brett

[Ron]

As for temperature control I don't think it would make a measurable difference.