Here in Maryland last year I left 2 windmills in pots outside all winter long and had no issues. This year since they were bigger and I also added a Pindo, 2 more windmills, a Canery Island Date, and European Fan I wheeled them into the garage when it got below 20 or there was snow. They stayed in the garage for a couple weeks at a time a few times. They are back outside now, I covered them with plastic earlier this week when we had 6" of snow, its supposed to be near 70 on Saturday and then I see a chance of snow on Tuesday. But since the temp is not cold I will leave them outside.

I had planned on putting them in the ground, but now I am glad I didn't. I think the coldest it got in my back yard was 4 degrees one morning. I did ride by a couple houses that have windmills, one house they were all brown and didn't look good. Another house has a larger one that still had some green but brown also. There is a pool company that has 15 or so outside and they had them covered. Have to wait and see how they make it.

I also have a Pigmy Date Palm and a Foxtail that I have kept inside over the winter. They aren't doing bad but I think the foxtail wants out!

Can't wait for it to get warm so they will start growing. :)

This was the strangest winter. It didn't get below zero in my area, but I lost a lot of non-palms because of the prolonged cold. This is a picture of my needle palms just one day after being crushed by snow (Sabal McCurtain also looks okay).

My protected trachys are okay. Some heat damage from having to have their protection stay on for such a long time, but they are okay other than that. Down the block a house has several unprotected trachys that had no problems at all last winter. This winter they are looking pretty bad but alive so far. My sick, small, and unprotected trachy had spear pull and probably won't be coming back.
Seems like trachys were a bit iffy here this winter but all the established ones seem okay.

I'm in NYC and we got down to 3F in my yard which is a bit of a cold spot compared to nearby stations in New York City.

-Alex

We had a very rough winter here in NYC (Bronx)was not expecting much success since my windmills were just plated this year. proud to say my windmills thrived in there mini green houses. It seems the cold does not bother them, just have to keep them dry. I used spot lights spiked in the ground facing the trunk. Only used the lights on extremely cold nights.

Mine look pretty bad. They have flourished without protection for years, but this winter was ferocious.