Minus 20F, Jason?
That's surprising, and off the top of my head, I would say, record-breaking. Am I right about that? I remember you stating something, like -13F, back in winter. You must've had another cold blast, either before or after the -13F.
My low for this past winter was -10F. Even that was colder than I've seen, in several years. I posted pics of some of my damaged plants. I had considerable browning to my Deodara Cedar, but it is now in recovery (putting out new needles). I always try to learn something from bad outcomes, and hope to do something differently for that plant, going forward. I learned that the upper limit of z6, is about the cold limit for Deodars, if unprotected, like mine was. It previously went through -5F, unscathed, in a prior year.
I also had some leaf browning to my Edith Bogue (few leaves fell off), but it too, is now getting ready to put out new leaves, at the stem tips.
However, as I discussed previously, Mimosas and Crapes are late leaf-budders. After my -10F winter, the Mimosa IS JUST NOW BEGINNING to bud...on May 20th! It has had a few z5B (-10 to -15) winters, in the past, and has budded out, as late as MID-JUNE, with wood damage. So, I believe that Mimosas are just z6 hardy, reliably.
Not sure if there is any wood damage, yet, to either my Mimosa or Crape, yet. I usually wait to see where the new growth starts, before I cut the Crape back. It may not die all the way back to the ground.
You have a wide range of "plant hardinesses", in your yard, so I'm sure everything hasn't done poorly. You had a few hardiness surprises, like the overwintered Cannas and Eucomis/Pineapple Lilies. Everything is not equally hardy. Those things that prove to be less hardy, will simply require protection, in colder winters, even as they come through normal winters, unscathed.