Ted, don't bet your prized plants on revisionist 15 year climatic trends. If you have zone 7 tender plants, you better mulch them. We had zero degrees during the blizzard of '93. When I was a young man back in the 1960s and 70s, scientists were predicting another ice age. Now Al Gore and his posse of scientists predict an ice cap meltdown. We have only been 'officially' recording weather conditions for about 115 years. We have had global warming and cooling many times in earth history. We are just one Mt. Pinatubo or Mt. St. Helens eruption away from a cool down. That is science we can count on.