Would a large cold frame be warm enough to grow citrus here?
We are about half-way North-South in Tennessee. Some maps put us squarely in zone 6, and others in zone 7.
We'd love to try our hand at some citrus, including 'cold-hardy' varieties of lemons, limes, oranges (if possible?), as well as things like Avocados.
We did a regular vegetable garden ~2,000 sq.ft. last year but are still definitely newbies.
We're looking at potentially purchasing a cold frame about 15x30 and 8' high - but not sure how warm it would really stay in the winter without adding heat. Thoughts? Is there hope for citrus here?