I planted two boxes outside the back door for winter: rocket, and land (American) cress, which is a great little plant: hardy enough to produce through the winter here, perennial (according to my sources, anyway - maybe it just self-seeds freely, which is effectively the same thing) and happy in part shade. I have some planted under trees as edible ground cover, but the these boxes are to be treated as annuals for winter crops.

so we get to garden year round without cold frames.

we have more problems with the scorching 40+ degree summers. i lose a batch of tomatoes and bell pappers each summer because they get sunburnt in the heat (some people use shadecloth to prevent that, but i'm too lazy to bother, since the evening breezes would blow them around).