Plant a Groundhog Day!
It might be tough to incorporate it into the same weekend you've already got your pagan group doing Imbolc and your Christian group doing Candlemas (which I'm not sure is official, and I must admit that I don't know what it is), and then there's Groundhog Day to fit in, too.
What's a good small-u universalist to do?
Build a fire to St. Brigid outside, then plant a groundhog!
You can read about Tu B'Shevat here:
It just occurred to me. When my Dad died and we didn't have anywhere to put his ashes for a year, that seemed kind of grim to me. Hell, it was grim. My mom hid his cremated remains in his sock drawer, for Pete's sake (hey Mom, I looked when you were out in California visiting that guy. Sorry.).
When we finally interred his ashes in front of the police station where he had been volunteer police commissioner for 8 years, it made it all right when we planted a pear tree over him. And now that pear tree is a big, gorgeous creature. It was a very Jewish thing to do.