I do believe I am officially now zone 7, wow. Thanks for posting this!

Here is a link that might be useful: {{gwi:1085160}}

I've always officially been zone 6a. But I typically won't plant anything unless it is hardy to zone 5. I guess I always expect the nursery growers to exagerate the hardiness a bit.

Very interesting. Thanks for posing this.

Ditto what cloud_9 said. Looks as though Z6 is getting mighty close to my little green acre. I also stick with things hardy to Z5 or colder but mostly for nursery-grown plants. From what I've observed the past couple of years, most winter sown perennials are a lot tougher & stronger than their nursery-grown counterparts.

Interesting. Perhaps 10 years ago, I ordered a large sturdy zone map from the USDA, and compared its contours to a conventional "political" map which displayed towns. The conclusion then was that my garden lay (but just barely) within 6a. Successes and failures on this plot of land, however, seem as related to factors such as shade (heavier under trees just getting established when we moved here in 1987), competition from tree roots, microclimates (we face south, and the land slopes downward, mostly from west to east, but also with a slight south to north decline), and soil types. This region of MA is a "sand and gravel" zone and some parts of our garden, such as the front where a sewer line went in, are sandy down at least 6 feet. A small brook runs along the north and east of the land, and the soil accordingly becomes more claylike nearby. As an example, hosta will grow almost anywhere, but plants moved from the sandy zone to the alluvial muck on the banks of the brook morphed from their former 1 foot height to 3 1/2 feet the second year.

That said, the northward zone creep is giving me fantasies of trying out camellias, if I can locate the right microclimate! We had a planting of lovely camellias alongside our house in Charleston, S.C. when I was a "tweenager" and the Navy stationed us there.

Sequoia,
I've been growing Camellias here in Providence (offically 6b) for about ten years. See my comments at another post here -"What does it take?" - and look at the last few posts. There are Camellias that can be grown in zone 6. Good luck.

Well, I'm off the 5/4 border and into zone 5. I've found zone 5 plants have done fine the short time I've been gardening as we haven't had a doozy cold winter yet. But, if we ever do have a winter with several really cold nights I'll probably lose some of them. I'm higher up in elevation and I haven't figured out how that affects me. My gardens face south, which helps. For now I'll give myself permission to not worry when I see a plant that only goes to zone 5!