We saw some wonderful warm-season vegetables on SQWIB's thread ...
We have some bok choy, choy sum and mustard greens. They are welcome and only available because they aren't in the open garden but in the better sheltered, backyard beds. As some of the greens were pulled, others were filling in.
It's just that they were in daytime sun and, even with many light frosts, the cold nights never shut down these greens. First frost: 22 September. The temperatures in the next few days should do it! May have nothing above freezing, on one or two of those days.
Of course, there are still 4 kale varieties out there, as well. Aaand, some collards ..! Have no idea how much cold collards can take. For that matter, I don't know about Portuguese, Italian and Siberian kale ... although one could have a suspicion about the last. I have grown them before but in the gardens where clean cultivation is the rule.