i think the purple strains do better in cooler climates. never grown any myself but have read threads saying the cool weather really brings out the purple
You see, most any plant has a turn of shade when the temps get cooler. And when non-purple strains of cannabis turn their leaves into darker colors it is a direct result of the temperatures falling and the plant nearing the end of its annual cycle. So, in summary, remember: cannabis turning purple when the temps get cooler doesn't make it a purple strain, it only means the chlorophyl has depleated from the storage centers in the plant and other compounds are displaying themselves in the form of darker colors as seen on the foliage. NOW....there are plenty of great purple strains out there and you should check them out along with doing some cold climate genetics searches. You'll like what you find. If you're serious about this and indeed have the neccessity for a cold tolerable strain then look up any of the early sativas or perhaps purple power( actual purple strain) and the Northern Lights. Good luck and GROW ON!
I think hollands hope is great for cooler climates. And like said above the purple strains. Check fresian dew from dutch passion it looks awsome for outdoor. Good luck