You might be a little late for your zone, but you never know what the weather will do. My ornamental kale kept growing with snow on it, until late January. This year I'm growing curly blue dwarf to eat and already have seedlings that are over 2" tall. Plan to cover with a makeshift cold frame from a glass paneled cupboard door we removed when remodeling.

Chard will die long before it is ready. It is not that cold hardy, and not that fast growing, compared to the other two. In Zone 6, I prefer to plant kale in July, while arugula reseeds itself also in late July. Surely you will use some of those 35-days russian varieties for kale, but IMHO it is too late for you. The other green that is in the same class as these two, in terms of cold hardiness, is the thing known as mache', or corn salad (it is in fact the best, IMHO).
It, too, reseeds itself in your beds.

Can you put a hoophouse over the bed, and seal it hermetically? In my hoophouses in Zone 6, they can get mostly through the winter despite nightly freezing. Arugula evolves through the winter into a rosette type of plant, with somewhat tough stems, but perfectly edible. Kale's eating quality peaks in late november but it stays edible for as long as it is dormant.

Forgot to add - try a root crop like carrots, parsnips or beets. Keep the carrots covered in straw when the snow falls and harvest as necessary. If the beets don't get big enough, you can always eat the greens on top.

Sometimes I think we are much too timid. What's to loose if we sow kale and it croaks under the weight of a frost? A few seeds and a little prep. What's to gain? Great satisfaction and lots more.....

Regular kale, like Scotch, is very cold hardy. The Tuscan kale stays green throughout winter in my zone 6 NY. This year, I'll se if the Scotch does as well. I suspect it will.

I like the Scotch kale, since it is more productive than the Tuscan. I grow both as cut-and-come-again, that is, I cut a 3-4-5 leaves from the plants (but leave the coarsest ones on the plant). I'm still harvesting kale from the plants I set out this spring. A few leaves of Scotch go a long way in a culinary sense, since its taste is rather assertive. However, chopped fine (like parsley) and cooked, it does great service added to all other vegetables. It's chock-full of calcium.

Chopped fine and cooked, it is delicious added to bechamel sauce. The sauce somewhat masks the assertive kale flavor. I haven't tried it, but I bet it would be delicious in a cheese soufflé.

Hope this is helpful.....

Here is a link that might be useful: kale seeds at Willhite, TX

Thanks for the link to kale seeds, ppod. Also, I agree with you about trying something regardless of the frost. Who knows, the weather may surprise us.

My kale produces long into the winter, even in the snow when the leaves get real dark green.

Chop fine, saute in butter and garlic then mix with mashed potatoes. Real good. I put it in Portuguese soup with kidney beans (stone soup), and the big leaves are perfect for pigs in a blanket.

I'm in Zone 7. I grow arugula throughout most of the year. However, it goes dormant from about December through March. The plants stay green, but they stop growing. The arugula begins to put out new leaves as soon as the weather warms a bit. That gives me something to harvest early in spring. However, the plants bolt within a few weeks, so I always put in some new arugula seeds as soon as the old plants begin to grow again. The earth doesn't need to be very warm for arugula seeds to sprout.

Lorna