I saw a Sochi tea plant in a catalog that was hardy in zones 7-10. Since I am in zone 6b, I was wondering if I could successfully grow these without wrapping in tar paper or anything like that. I am down in a valley, so there wouldn't be much wind. The space I would have for it would be right next to a south-west facing untreated pine siding wall. If it would help, I could put on a shredded wood mulch. Would this be a good idea, or a waste of money?
No. I bought a small Sochi tea plant in the spring of '12, and it took some serious damage that winter, even though it only dropped to 5 degrees Fahrenheit that winter. This past winter, the plant died, even though I protected it with a bushel basket covered in hay. It dropped to -4 degrees, and everything froze almost 2' deep.
Apparently, the advertisement was being optimistic. Sometimes, it matters more how long your winter is rather than how cold it gets. Often broad-leaved evergreens like tea have a difficult time in long, cold winters. In an area where it dropped low for only a month or so, I suspect these would be fine.
Check your zone online. I live in NYC and used to be zone 6. I am now listed as zone 7. Due to global warming many of the zones have recently changed. I have also had good experiences with calling the seller and asking for advice. They are usually very helpful.