I have answered my own question lol. I changed my keywords and found some great links. Here they are just in case anyone else has the same question:
http://bonnieplants.com/library/which-veggies-for-which-season/
http://garden.lovetoknow.com/wiki/8_Frost_Resistant_Vegetables

My savoy cabbages went through two polar vortexes last winter. Temperature was minus 6 near the house and perhaps lower in the garden. They were wrapped in two layers of medium weight row cover, but still--and they showed no damage at all.

Cold hardy veggies don't keep growing through winter. They hunker down and sit out the extreme cold under protection, then start growing first thing in spring, when the days get longer in late Feb. Until then there is not enough light to run them.

I plant a frame with spinach and parsley, which gets closed up in December. It has a tempered glass top (old shower door) so it doesn't collapse under heavy snow. This gives me spinach to pick in March.

Deer get very hungry in winter, so anything I want to grow through winter -- including cover crops -- gets covered to keep them from eating it.

laceyvail, that is amazing! This seed is on my list.

planatus, this brings up another question. We have weird weather here. So if it has a hard frost but then the days are nice, will the plants continue to grow? I am growing short term fall crops but they may experience a hard frost or two.

gardengal,

Yes. Frost-tolerant plants will continue to grow. What eventually kills them is the combination of repeated hard frosts, cold days near or below freezing, and lack of sunshine. Unlike with warm-season crops, this is not a sudden event. But if your winters are mild enough (no exposure to subzero F temperatures without snow cover), many will survive through the winter and regrow in spring.

The hardiest cold-weather crops are mache, claytonia, kale, tatsoi and spinach. These will take the teens Fahrenheit without any kind of protection (not even snow cover) provided they have been exposed to some 20s first.

Swiss chard, beets and radishes are less hardy. They can handle the mid-20s and higher, but not teens.

Lettuce is the least hardy cold-weather crop, kicking the bucket if it gets below the mid-20s F or in some cases even high 20s F.

This post was edited by Slimy_Okra on Wed, Aug 27, 14 at 19:22

Thanks, Slimy_Okra! This helps so much. I don't have much experience with fall crops so I was a bit confused about it.

Re the savoy cabbages: I sow them in mid June, transplant into garden in late August. Where I live, they must be covered with row covers from the time they germinate to protect from flea beetle and cabbage butterfly. I start them in little starter cells, transplant to bigger pots with the whole business under a little row cover green house held up by metal hoop things and all sitting right in the garden. Of course, I check them daily and water daily if it hasn't rained. Lots of work when you're busy with other stuff, but I've got it down to a simple system, and boy oh boy, harvesting those delicious sweet cabbages in Dec. and Jan is really a treat.

Johnny's Seeds in Maine has some great reference material on their website. I've had spinach winter over outside with little snow cover. It looked dead but started growing in the spring for an early harvest but a high tunnel is much better. They have info on their website.

Leeks, Parsnips and Brussels Sprouts are three more classics of the Winter garden here.

laceyvail: I bet that does tastes good when prices are so high and produce is terrible in the stores. I will have to figure something out too :). I need a bigger plot or a new place.

Thanks, defrost49! I will look up their site. I am going to try that with my spinach. I had no idea it did that.

Thanks, floral_uk! I need to go pick those ones up. I've been wanting to try Brussels Sprouts for awhile.

Well, "extreme cold weather" means different things to different people. To many, "hard freeze" doesn't fit that. Here in Texas, where we almost never have what I'd call "extreme cold weather", we have regular winter hard freezes where the temp dips into the mid-20s. Sugar snap peas survive that beautifully. In fact, they seem to survive down to the low 20s.

Of course, you won't get fruit production until early spring.

We don't often think about trellising plants when we think about ground-hugging winter root and leaf crops.

If you want to research more on the topic, look in your library for books from Eliot Coleman. He has a lot of useful information and suggestions and his extreme cold weather is that of a Maine winter. I believe he has worked with Johnny seeds too.

That is true, Dan! You know, our winters here are really iffy. We can resemble weather in Northwest Montana with tons of snow storms and/or temps in the teens and some winters, lately, are more like Seattle. But we do have hard frosts under 32. Seems to change every few years. Off topic: but the leaves on the trees are starting to change here. They usually don't change till Late Sept. early Oct. Was predicted to be a warm fall but I am beginning to wonder. Hard to do a fall garden here :-/. I might try those peas and see if they make it. Fun to experiment.

Thanks, tishtoshnm. I will check those out. I am always looking for a good book on this topic!
Edit: Just checked out my library and they do carry his books. Yeah!

This post was edited by gardengal13 on Fri, Aug 29, 14 at 18:16

Hey you never know what late fall may turn out like. Some of our warmest Novembers have followed our coldest Septembers, and vice-versa.

That is true too, Slimy_Okra. Here's hoping :D!

Red Russian kale is in a league of it's own for cold hardiness.

Also want to mention Winterbor Kale, the hardiest of all the kales. Seed was very hard to find this year so for the first time in many years, I'm growing another variety. But in a winter that is not too awful cold--that is, not a lot of temps heading towards zero, the kale begins new growth as soon as days begin to lengthen in Feb. The flush of new growth comes from the nodes where the old leaves meet the stem. The new growth looks a lot like broccoli raab or Gai lan, and is sweet and very tender, tasting more like broccoli than kale. You can eat the whole thing--leaves, little heads and stems. I start picking when there are just the new young leaves and add them to salads.

I think I am going to try the varieties that chickencoopcomposter and laceyvail mention on my deck. With fall coming, the leaves on the tree blocking my deck fall so there is more sun. My garden is mostly at a community garden but I could plant these two here. Thanks for the variety ideas! I wonder if I can find the seeds for Winterbor?

This post was edited by gardengal13 on Sat, Aug 30, 14 at 19:22

Nagoya Kale from Johnny's Seeds lived through last year's winter in Southeastern, MA. That's a true test! It had very bright pink foliage throughout winter, and lived as a perennial through the summer as a dark green kale plant.

Want to mention again, that you cannot sow savoy cabbage and kale now and expect them to do well. I sow my cabbages in mid JUNE here in zone 6A and the kale in mid JULY. And if you're planting in containers, neither may do well in the temperatures I described--much less root protection.

Yes - to reiterate what lacyvail said - these brassicas are tough once established but at this time of year they should have been transplanted and growing in their places for several weeks already. We just had our first picking of curly kale tonight and we'll be eating it until next March/April. The plants are two feet tall already. The seed came from these people. They are a a UK firm but when I googled there were plenty of US suppliers.

Here is a link that might be useful: Winterbor

I understand and normally I would start earlier. However, our summers get way too hot and it makes it a bit tricky. For example, last year it was 90 one day and 60 the very next day. There was no slow cool down and it stayed in the 60s for the rest of the time until it cooled down more. I planted my broccoli when everyone told me to last year according to my zone, and it all bolted. I can grow them indoors but they get too big and there is nowhere to store them. So I am experimenting this year. I might only have young leaves to eat and that's ok with me. I am just trying to get it down an area that is 6a but really could be 4a and 7a at different times in the season. It is such a weird place to grow in! I think it is because it's sort of a mountain area and we used to have 80s all summer and strong cool winters with lots of snow. I appreciate your guys help! You have all inspired me and gave me some new varieties that I would never had thought of :). I really love this forum!