A: It’s weather related. We’ve seen this on a lot of boxwoods this winter.
Your boxwoods were thrown off by the weather this fall, which was warmer than usual far later than usual. Boxwoods were not the only plants fooled – redbuds broke into bloom again, and Japanese maples put on a new flush of leaves after they’d already begun to drop them!
Basically, your plant wasn’t fully hardened off for the first 20-degree or so cold snap we had. If your flowerbeds were dry, this was a bit worse. And if your sprinkler was still operating automatically the night the cold hit, that’s a lot worse.
Come Valentine’s Day, trim off any burned foliage from your boxwoods, and fertilize toward the beginning of March. Boxwoods are resilient and grow with decent speed. Almost all of them will recover.