Some are relatively easy to grow.
Siberian kale is as hearty as it is rugged.
Corn salad make a perfect complement and, depending on your climate, can be grown with little or no protection. Extending the growing season is a challenge that is amply rewarded, and does not necessarily require fancy or expensive protection devices. Many salad greens besides those mentioned above can be kept growing throughout the winter and spring with simple cold frames or portable coverings called cloches. Cloche is a French word for bell. First introduced in the 17th century, bell-shaped jars of blown glass were set over plants in the garden to extend the growing season in the fall or to force lettuce in early spring.