Answer: Washingtonia robusta is rated hardy to zone 8b -- roughly in the 20 degree range. While I have seen palms in the Norfolk area wrapped in plastic, that is a bit warmer than your area. The microclimate where it is planted might make a significant difference to the odds of success, as would the weather each winter, the genetic make-up of the plant, its overall health, and so on.
To try to protect it, you would need to build a wire cylinder to fit over the foliage, line the cylinder with plastic, place it over the palm and then stuff it with dry non-matting leaves or straw, then close the plastic to keep out moisture. This is not very attractive over the winter and can be quite a technical feat as the tree grows taller. I snapped a photo of some in the Norfolk/Virginia Beach area late last fall. You can take a look at it at
You may need to cut and paste the url into your browser to make it work correctly.
You might want to check with local professional nursery staff and/or your county extension to see if anyone is trying that in your area and how successful it has or hasn't been. Unfortunately, I would not be too encouraging since the foliage can deteriorate in cold spells even if the plant is not actually killed outright. Good luck with your palm.
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