I've been keeping the two kale plants I mentioned in a cold place (my vestibule) for a time. (Evidently our winters are too cold for kale to survive the winter, at least sometimes. The plant I got these kale seeds from had survived an uncharectaristically-mild winter and produced seeds the next summer. I have tried to leave mostly-harvested kale plants in the ground over the winter since then, but they didn't make it.) These recently started putting out new leaves, and I've put them in a bright, south-facing window where my houseplants are.
Leafy vegetables such as lettuce, most herbs, and kale don't need quite as much light as other vegetables such as tomatoes, corn, or beans (and they're also smaller!), so I think they're supposed to generally do better indoors.