I just bought Chuck Hayes from Triple Oaks and planted it. According to the nursery people, with proper mulching, it should be OK in Central Jersey. I will be able to tell more by next year....
Padma.

Oh, I forgot.. I also got 2 gardenia jasminoides 'KleimÂs Hardy' from big dipper farm on the internet. I planted about a month ago. These are only 8" or so long but bushy. So far, the leaves are a bit yellowish green and I am hoping that it would change with the raise in temperatures. I will definitely let you know how would these plants do in a year.
Padma.

You should try to search this one. Although you might not get specific to NJ, there are a few who posted in similar climates. I remember seeing a couple in the Rock Garden at the NY Botanical but I always forget to check on them.
Here is a link. The first thread is cute if you have not read it yet.

Here is a link that might be useful: Hardy gardenia search