Q: I have 2 young windmill palm trees and several different varieties of young crepe myrtle trees. I live on the border of zones 4b -5a. [upstate NY]. I've gotten so many different answers to my one question, will all these trees survive up here? If so, anything I should know about wintering them up here [i.e pots vs. inground]? Posted by Robert
A: Unless there's some new variety of Windmill palm out there that can take cold climates, you'll need to bring this plant indoors over winter into a sunny space if possible. Even if you plant it in the ground, you can dig it up, put it in a pot to store it over winter.
Regarding the Crape myrtle, there are some more winter-hardy varieties available but I think you're still to far north. If you plant this, it will likely die back to the ground in winter but you will likely see new sprouts next spring. Unfortunately, you don't buy and plant a crape myrtle to have it die back to the ground each year. I'd look for something more tolerant of your climate. Your county extension service can provide some good alternatives. Good luck.
i am in zone 5 and planted 3 crepe myrtles recently. i chose an area that offers southern exposure, and there are multiple large stones around the planting (hiilside supported by stone retaining wall) to warm the ground. i am thinking that this little microzone is 6 and they will do well...we shall see.
my point is you can always try if you have an idea.