Hardiness
With protection, some of the more hardy species may be grown in areas as cold as USDA zone 4. Candidates for the colder zones are Trachycarpus fortunei (Windmill Palm), Rhapidophyllum hystrix (Needle Palm), and Sabal minor (Dwarf Palmetto). "Zone pushers" (who grow plants outside in climates that are generally too cold) often plant palms and other tropical plants on the south facing side of buildings, a micro climate with higher temperatures. With good protection, a palm can survive in a much colder environment than otherwise.
The needle palm (rhapidophyllum hystrix) may be able to survive unprotected in USDA zone 6.
Read more about this topic: Hardy Palms