Collard greens grow well in many parts of the world, are robust and beautiful plants that produce large amounts. And they do not have to be cooked for an hour with a ham hock (though by all means do if you can). There are many quick and fresh preparations for these delicious greens. You can even use tender, young leaves raw as in the salad with apples and walnuts.
Collards keep well in a plastic bag in the refrigerator for 3-7 days or so depending on how fresh they are to begin with.