Look for kale with firm, deeply colored leaves and moist hardy stems. Kale should be displayed in a cool environment since warm temperatures will cause it to wilt and will negatively affect its flavor. The leaves should look fresh, be unwilted, and be free from signs of browning, yellowing, and small holes. Choose kale with smaller-sized leaves since these will be more tender and have a more mild flavor than those with larger leaves. Kale is available throughout the year, although it is more widely available, and at its peak, from the middle of winter through the beginning of spring.