Well I feel quite idiotic.
rainbowgardener wrote:@ Mr_Bobo:
You can find Sunset climate zones for anywhere in the US here:
https://www.sunset.com/garden/climate-zo ... 000036421/
Here's a climate zone map for Europe:
European climate zones
These are comparable to the USDA hardiness zones, not to the Sunset climate zones. That is these European climate zones, like the USDA hardiness zones are based solely on how cold does it get in winter. The Sunset is a more detailed system that takes in to account winter cold, summer heat, humidity and precipitation etc. In fact if you compare the European climate zones to the USDA ones:
they are exactly the same. In other words, zone 4 corresponds to the same average minimum temperature range in both systems. That's very helpful, it means here in Ohio zone 6, I can look and see that my winters are about the same coldness as much of central Europe, much of Poland, Hungary, Bosnia, Serbia, etc....