How far north do palm trees grow?

In 2007, the BBC reported that Ian Imrie of Bridge of Earn, Perthshire, Scotland, had grown a 22 foot windmill palm tree in his garden. At roughly 56.35 degrees north latitude, this palm tree was thriving thanks to the warm Gulf Stream current in western Scotland.

Imrie also told the BBC, "We think the exhaust from the house's heating system, which comes out nearby, has raised the temperature and helped it grow."

The windmill palm (Trachycarpuspus fortunei) originated on the island of Zhoushan, which is south of Shanghai. Windmill palms thrive in parts of Britain, and they have also been grown in Bulgaria and Switzerland. Windmill palms have been grown in Seattle and Vancouver. Florida-Palm-Trees.com reports that windmill palms and needle palms have been successfully grown in Alaska.