Look for kale leaves that are a rich, dark green and have a bit of a crisp texture to them. If they’re in a bag and you can’t feel the leaves, try to ensure that the color is uniform and none of the leaves look slimy or wilted. Kale that is packaged typically lasts for 3-4 days, so long as you don’t wash it before you store it. Consider rinsing/washing your kale leaves to be certain there’s no excess dirt or other grime left behind.