A kale plant, from my experience, usually dies in the summer after it blooms and sets seeds. So, if you want a continuous supply, you need to stagger sowing. However, I put some in late last spring, harvested them selectively through the summer, protected and harvested them sparingly through the winter, and harvested them vigorously when they surged in the spring. Then they went to seed. One of the six plants survived the seed-bearing process, so it's got small but harvest-able leaves in mid-July. Seed that fell in the lawn during my seed-saving operation produced plants which are ready for light picking in late July. In early-July, I started sowing the saved seed, so I also have some very small plants to set out soon to start the process again. Has anyone tried "castrating" biennials to prevent them from spending their energy on seeds, to keep producing tasty leaves year after year?