Windmill palms (Trachycarpus fortunei) are considered the hardiest of palms. Some sources say zone 7 is fine, and even note survival of short dips to -10ºF. My winters are overall warmer than in the past, which is good for some things. But the weather is definitely not normal, so unusual cold is still possible. Nonetheless, if your palm is too big to protect, bite the bullet and find out if it can handle winter without protection.

I lost 2 Windmill palms to the winter of 2013-2014. S. Jersey usually gets hit with a prolonged visit from the "Polar Vortex" at some point every winter. Rarely goes below 5 degrees but the duration of the cold weather is what takes them out. I'm not ready to bite the bullet. Hopefully someone out there has some experience protecting a large palm.

Thanks! I have seen some PVC wrapping schemes which may be sturdier and more attractive. I may need to give that a try. This past winter it looked like I built missle silos in my yard. They looked green as can be when I unwrapped them in March.

At the very least, wrap some Christmas lights around the trunk (C7s maybe) and if you can throw a tarp over the plant in the worst part of the winter, that would help. You will likely get cosmetic damage to the fronds if your temps go below 5-10 degrees, but the plant should have a better chance at survival. Take care the lights don't touch the tarp or it could start a fire.

I saw your other post about this same issue. After reading BOTH of your posts or threads about the Trach Fort. I am thinking I can overwinter MY Trach Fort in my greenhouse only adding some C-9 lights. I also hope that YOU are successful overwintering YOUR Trach Fort palms.

I AM very interested in what type of lights and wrapping you used in those pics above. I may need to eventually have mine planted in the ground in MY zone 6a Pa yard.

I currently double cage my windmill palms. I use regular garden fencing you can get at Lowes/Home Depot. Tallest they have is 6 feet. First I tie the fronds together as close as possible. Neatness counts. The inner cage is wrapped around the trunk with about a foot of space between the the trunk and cage. I clip a strand of 25 C9 lights inside, working from the bottom up to the center spear then fill with dry leaves up to the center spear. The outer cage needs to be wide enough to clear the fronds by several inches, and tall enough to reach just below the height of the tree. Then I create the "dome" by arching a length of caging and interlocking it to the top. You need a high arch so the weight of snow will not collapse it. Then I wrap the whole thing with 2 mil painters plastic and duck tape. Make sure it is securely staked into the gound. I can't stress that enough. I turn on the lights overnight when I know the temps will go below 25 degrees F. During cold snaps when the temps never get above 25, I keep them on continuously. Due to the height of my big tree I had to interlock two 6 foot sections together to make it tall enough. That was a challenge. This winter it will be more of a challenge. It's barely mid-July and it has already pushed out 7 new fronds and looks like it has another foot in height.

Thanks for the info. I have a few years at least til I will transplant mine in the ground, but, this info will be here to look up again. I tried this already with a palm BUT I hadn't used big enough lights, I used NON led tiny lights, and it froze. I already have the C-9 NON led's for using for my palm in the greenhouse this coming winter. The greenhouse may get cold enough still to freeze the new one without lights. I am not sure which heater I'll get to use. It will be a space heater like you use to warm a room. A GW er on the succulents subject uses a room heater in his, so, I will be trying that in mine. I just got my greenhouse about 2 weeks ago, so, this will be my first year with heating and storing zone 7 ish plants in a greenhouse. I'm using extension cords, the greenhouse has no electric in it. Later.