(Brassica oleracea) Kale may be the hardiest of the cabbage kin. It excels in cold weather, tasting best after frost has kissed the tender, succulent leaves, and making moderate growth whenever there is even a slight warm spell. Start in containers indoors or direct seed in the garden in late June. May also be sown indoors for early spring planting. Kale thrives in rich soil, heavy on organic matter, and moisture retentive but well drained.