They cant grow without protection in a zone 6, but they can definitely grow with a little extra protection. It also depends on what zone 6 you are in. Palm trees hate freezing weather with wet weather. If you have a very hard freeze after lots of rain, or lots of snow, and then the constant thawing and melting that comes with snow, then your palm will rot at higher temperatures. So protection from winter rain and snow is very important.
I put plastic garbage bins over mine with Christmas Lights around the palms. It keeps them out of the cold winter rains and wind and also adds a bit of extra heat to them on those colder nights. Works well in my zone 7!

Good luck!
-Alex

In the winter, we get a lot of rain, snow, and ice, so lll make sure to protect the palm

7b is about the limit for windmills to survive winters unprotected from what I've read. Maybe 7a, if they are in a microclimate and protected above from icy precious by roof eaves.

Try needle palms in your zone too. They could eventuality go unprotected after established and protected the first few winters.