Thanks Bill. Looks awesome.
I also did a bit of experimenting here in eastern washington. I use portable tunnel row covers which works ok for early spring and late fall/winter.
This year I experimented with kale, beets, spinach and lettuce (without row cover). Here the weather was uncharacteristically mild. The greens actually like the light freeze down to the high 20's they do just fine. Sweetens up the flavor quite a bit on the kale, beet greens, spinach and lettuce.
Planted kale and beets July 15th, spinach and lettuce August 15th. All still producing til around December 10th when the single digit temps and snow took over. I probably could have covered with row cover and still get something but once snow starts falling it's not so easy.
Here's my last large harvest of greens (also some resilient celery stalks) from Nov 30th.