I put in broccoli plants late in the fall of 2006. They pretty much just sat there doing nothing all through the winter, went through a few frosts (I think?) unscathed, and then proceeded to provide us with lovely fresh broccoli in the early spring-- say March to April.
I’m in Silicon Valley, for reference purposes. No snow, except waaaaay up on Mt. Hamilton, but generally a couple of frosty nights.
Funny you should bring this up-- I didn’t spot any broccoli at the nursery this past fall, so I just started some seeds in my little inside window box in peat pots. Hopefully I’ll be moving them out in a month or so…