And the lesson learned is: Don't plant anything after 9/1.
It's not that I can't. The peas are alive. At least, the ones the slugs haven't completely decimated. But the growth is slow. So slow, that I might as well have just planted them in the spring. Same goes for the broccoli I'd planted back in November. It's not dead, but it isn't exactly thriving either.
Yes, I could spend my frosty nights with a flashlight looking for slugs. I could put row covers over the peas, but honestly, I'd rather take the time off.
So: I'm not considering the Double-Triple Pea Experiment a failure. It was actually a success given the goal was to find out how late sown peas would do. The answer is: Not well enough for the trouble!