Japanese maple never lost their leaves
I found this article from a blog out of the university of Maryland:
it says this: An unusually warm autumn followed by a quick cold snap likely interfered with the trees’ normal winter preparation processes.
so I looked at our weather last year. November we had weather in the mid 50's a lot of the month and December we got cold and stayed that way.
The article finishes with:
There is nothing you need to do for your Japanese maple at this time. If your tree was otherwise healthy, new growth will emerge in the spring and the old brown leaves will drop off eventually.
So, I think, since there are lots of buds on your trees, everything is going to be okay!
Thanks for asking!
Whew! Thank you Sue.