Also called napa cabbage, 'One Kilo Slow Bolt' has a delicate flavor, a soft texture in between that of lettuce and regular cabbage, and tight heads have a creamy yellow interior. Grows with ease in fall, and can be sown in spring if care is taken to protect young plants from temperatures of 50°F or below, which may cause plants to bolt. Grows best at 60°-65°F.